Most of the imperfections in GT seem really stupid, leaving you wondering, "Why or how?"
For the fifteen-millionth time car sounds are probably 90% bad. The sound effects ARE, as a few members mentioned in another thread generic.
We ALL (Or at least most of us) know that not every blow-off valve sounds the same, some flutter and some hiss.
We ALL (Or... at least most of us) know what different engines should and should not sound like, race exhaust or not. While on the topic of exhaust systems, I will mention the lack of, as someone mentioned (in another thread), "burbling/popping."
The physics feel okay to me (despite obvious flaws like aero, top speeds, lift off oversteer, tire modelling...etc), keeping in mind that I'm not a racecar driver, nor have I ever raced in an organized event, but I don't think I'm alone when I say that I have test driven friends' cars and driven other cars to some point with high performance in mind.
They have MOST of the basics down with physics.
Moving on If I could take over Kaz's job, having learned what is necessary to do so, I would put forth effort to:
-Improve sounds across the board.
-Improve physics across the board.
These are IMO a given with each installment of the game, at least regarding aspects that the dev' team wants to improve.
The A.I for the fifteen-millionth time are another issue. Most races are easy simply, "time attacks with obstacles", and some can be difficult. The races that can be difficult are ones where the lead car has nearly lapped you by the time you begin the race. Although most of the races are like watered down kool-aid, there are a few (and I do mean FEW) that I found decent. The redbull X challenges for instance provides an example where the A.I seem abnormally sharp.
If they could be intense like this all of the time, then that would be great. So with that said I would also improve:
-A.I agressiveness/drive, and ability to rationalize.
I'm not leaning on the GT series to get my "car fix" anymore though, so I won't be upset if the GT series half-cooks the next steak. I honestly will probably just buy it anyway despite its flaws. The game has been a part of my life since I was four years old, and nothing PD and Kaz have done, has hurt me or negatively affected my life.
I know others feel different though.