All references are to the PS2 version of the game and it's controller. Some of these issues may not apply to the PC version but the PS2 is the only one I have played.
Non-gameplay:
1.) Improve Interface, menus, and general usability. Generally speaking...
A.) Make it easier to navigate menus and in particular change ratings/create players
B.) Condense the number of areas to make more information available in one place, or generally make the areas that do exist more useful.
-Use the Redorder Rosters screen to double as the place where you can edit players. On PS2 for example, R2 is "View Player"... R1 can easily be "Edit Player" which would open the edit player screen.
-When editing a player, showing the player standing there doing clapping animations is totally unnecessary. Remove that and you can eliminate the need for so much scrolling. Either that or make the list continuous (scrolling up from the top item takes you to the last item in the list.
-END the process of scrolling through jersey numbers and colleges. Selecting the jersey number should open a screen with a matrix of numbers so setting a created player's number to something like 55 is not such an annoying process. For colleges open a list of all the colleges beginning with "A", allow buttons such as R1 and R2 (or the equivalent on other consoles) to scroll through the letters of the alphabet.
-End having to scroll through the different types of gear. Make it function like selecting a tattoo.. Selecting, for example, "left elbow accessory" opens a graphic display of all the different types of bands/sleeves, etc.
-Add the per-game season stats to the Reorder Rosters screen in season/dynasty.
-ADD MINUTES PER GAME to team stats pages.
-Change team stat viewing to be more like ESPN.com, for example. Show stats per game on the default screen. Pressing a button then allows you to switch to season total. To really impress, add "per 48 minute" totals to a third screen.
-Revamp the league leaders layout. At the very least, include the team the player is on in a more obvious manner than showing the logo behind his face, add the "view player" capability so we can see his other stats, and change the order of display to be more intuitive. Ideally though the leaders page would behave more like the team stats page. Sort by any of the categories, display the top 25 in each, with ability to switch from per/game to totals and per-48 minutes. Should also implement a "minimum attempts" for 3pt, FT, and FG percentages. Allow to exclude/include positions, for example displaying only the top centers.
-Add efficiency rating as a stat.
2.) Other General improvements/additions to player creation, identities, ratings, and in-game behavior.
-Keep improving face creator. Most importantly, skin tones, hair colors and hair styles. I consider these to be most important because they are really the most visible aspects of created players during game play, and should not be that difficult to have more of. (As opposed to facial features which I would presume is quite an ordeal for a graphics team). Allow a MUCH greater array of skin tones.. very difficult to accurately model lighter skinned african-american players, hispanic players. Choosing between 5 colors of skin is kind of an embarassment. In the same vein, allow a greater specturm of colors for hair. Also provide more than 10-15 hair styles.
-Give ability for more than just 2 positions. Ideally add "GF", "F" and "FC" designations for players who would then be equally able/likely to play those two positions, and then a secondary position of something else. For example, Dirk Nowitzki would be a "FC" with a secondary position of "Small Forward". This would allow more versatile players such as Dirk, Garnett, etc, more flexibilty.
-Additions to ratings:
- Field Goal range - shots taken beyond a player's given range start to get increasingly inaccurate. This alleviates the problem of centers who have very good outside jump-shots but who shouldn't necessarily have high ratings in three point shooting.
What does "defensive awareness" actually mean, in terms of gameplay? To a certain extent it should include defensive "reaction time" for a player. If it doesn't or isn't designed to do that, make a rating that does. For example LeBron James is a top steals guy but is by no means a good defender.
Include a ratings that would be based on a scale of 0-10:
- -Aggressiveness (propensity to foul)
-Hustle (propensity to get after loose balls, rebounds, etc)
-Shooting Range (where each number increase means approx 3 feet of shooting range. Shots taken outside the player's range get increasingly inaccurate. Could also just make this a 1-30 rating)
-Leadership (higher ratings given to veterans, results in slightly better team play during regular season. Has a larger impact during playoffs.
(Make these 1=10 for simplicity's sake. Probably not necessary or even possible to declare Player A as having a "Leadership" rating of 54 versus Player B as 56. Also these rankings should accordingly not have as great an effect overall rating.)
-"Bias" sliders for players.
- For example, inside game vs. jump shooting. Fixes the problem of power forwards/centers in the Nowitzki, Walter McCarty, Cliff Robinson molds playing inside too much during gameplay compared to their real-life counterparts. 83% of Nowitzki's shots come on jump shots, compared to 26% for Dwight Howard. Similarly, guards and small forwards who tend to drive and slash more (such as Payton who makes 38% of his attempts from inside) would have that part of their games reflected in gameplay, and guards that take more jump-shots (Damon Jones, 94% jumpers) would also behave accordingly. Could be as simple as a slider where 0 would represent a 100% inside player and 100 would represent a 100% jump shooter. Obviously noone would be that extreme but it would add a great touch.
Another possible would be "dunk vs. layup" slider for players. Right now there is a dunking rating which seems to rate both a players dunking ability and dunking frequency. Would be nice to have this separated into two to create more player accuracy.
-More varied gear options. I notice that the bicep bands players are wearing are a lot thicker than available in the game. A great touch would be a "mask" (for Hamilton, in particular, and perhaps for players who suffer a face injury dyring a season, have that player don a mask for a while afterwards.)

3.) Specific Gameplay/In-Game Issues Most of the common issues people have said. Those I repeat I repeat because they're important.
-Fewer blocks on jump shots
-There seem to be too many lob passes. These are infuriating. Players should use bounce passes to get by defenders.
-Better fast break action. Wing players always pull up.. If your player is pushing the ball (using turbo) your players should fill lanes and go to the hoop, and if nothing materializes they curl around and back out. On the other side, defensive players should react better to fast break situations. In particular 1-on-1 scenarios need to be executed better. Backpedalling defenders should be at more of a disadvantage. Also, poorer dribblers should have their speed SEVERELY reduced when trying to sprint and dribble. Lumbering centers should be even slower when trying to sprint-dribble than they are, and should be 500% more susceptible to steals.
-Even outside of fast-break situations, passers should "lead" their recipient. If a player is moving the pass should be put out in front of him, especially if it is a skilled passer.
-Long passes should be intercepted or knocked out of bounds more frequently. Too easy to beat a press just by heaving a long pass down court.
-Agility of players in sprint, especially with the ball, should bee decreased more than it is.
-Players should hoist last second shots with greater ease.. AI should "know" how much time is left on the clock and rush to get shots off instead of doing their usual pass-reception, turn, jump shot animation.
-Animations should end faster. By this I mean there shouldn't be a delay in reactivity after an important thing happens...If a players shot gets blocked he shouldn't just stand there while the ball falls to the ground 4 feet to his left, and neither should the guy who blocked the shot just stand there.
-Diving for the ball is nice but the ball should be "looser". A dive onto the ball shouldn't necessarily mean the player gets clear possession and if a player is in possession of the ball on the ground and a defender can attempt a steal while near him, a tie-up should ensue, or the AI player should call time out if he can't pass to people. Passes from players on the ground should also be intercepted with greater frequency.
-Increased playbook/plays capabilities. If not create-a-play then at least diagrams explaining how the plays and sets in the game work. Give each team a group of basic sets, ideally based on their NBA counterparts. A team should have 4 sets in it's book, not counting the "plays" such as "pick and roll", "isolation", etc. These should be mapped to dedicated buttons. The actual sets (1-4 High, Utah, Stagger, etc) should have better continuity and actually BE plays.
-Generally speaking interior defense needs to be more stingy, exterior less so. Levels of scoring can be accurate but field goal percentages tend to be a bit high in gameplay and I find this to be due to it being a little too easy to gain access to the interior and then score. An increase in help defense on dribble penetration and feeds to the post would clog the middle and open the exterior which I think would more accurately reflect reality. Open looks at jump shots seem rare because defenders are playing too closely to their men on the perimeter and rarely stray to play. This and the lack of off-ball picks due to the abysmal so-called "dynamic" offense being used by default make it difficult for AI players to get open for outside jumpers which are still a major part of the game and an admittedly lower-percentage shot.
-To compensate for this, scoring inside should be tougher. Inside scoring/layup ability can be turned down but this should not simply result in more of those "avoiding contact, throwing the ball up" animations. There should be a larger array of power moves especially for power players with higher Strength ratings. This is just for esthetics, though, the shots shouldn't necessarily be more likely to go in, especially if there is more traffic down low as suggested above. Also, its seems like even with "in-air collision fouls" at 100, there are not many fouls called down low. Attempted blocks of inside shots should result in more fouls than they do. Perhaps a double-touch on the "block" button should represent a more physical block attempt or foul attempt to stop an easy layup. Commentators complain that the defensive player should have fouled to stop the easy basket but there's no way to control that!
-Fix the problem of shots coming from beind the backboard. Make players more aware of where the hop is when executing inside shot attempts. They should never be muscling or leaping into a position that foreces them behind the backboard, ever.
-The "take charge" button should not freeze your player. The animation should be quicker and you include whatever movement the player is attempting. This more accurately reflects what a player does.. If he goes into position too early the offensive player can adjust to avoid him. The defensive player has to either let him blow by or move/lean over and probably take the blocking foul. If the user shifts position while pressing the "take charge" button then at least you are causing contact.. you're less likely to get the charge, more likely to get called for a block but the shooter is less likely to make the shot. Similarly If you press the button to get in position too late, you'll get called for the block or flop and get a no-call. This would create more realistic action and decision making on the part of users trying to play defense on drives to the hoop.
-Display more stats. Can't stress this enough as virtually all EA Games from Madden to NHL to NBA have never really stepped up in this respect. After baskets, etc, show how many points the player has. Would be especially nice to also display season averages.. "6 assists tonight, >>Season Avg. 5.4", etc. Season/career three point percentage overlays for players who hit (or miss) a couple threes, etc. More in game information during season and franchise modes to make the games more interesting, "tell the story" of the game, and increase the TV feel of things which is what most gamers seem to be looking for. Could even add a slider like the one for in-game replays in case people find them to be too much.
-Sound issues:
Improve sound quality and realism. Make crowd noise more responsive to runs for the home team, crunch time, and playoffs especially. Have dead crowds for poor teams or blowout games against the home team. Particularly lame/inaccurate sounding effects right now are the buzzer, whistle, and players bumping into each other.
Separate volume controls for in-game sound effects and menu sound effects.