The suggestion threads are indeed quite useful and i also hope they finally use our customer feedback, but on the years I spend here at GTP the issues people had gripes with all this time have not been addressed at all, which leads me to believe either they don't really care what is said here, or they just don't bother translating it in Japanese.
Maybe this is the first time that GTP has offered such a structured approach. Maybe there have been other priorities.
I'm a newcomer to GT, having started with GT5 just weeks before GT6 arrived, but I do observe that GT6 addressed things that I recognized as GT5 weaknesses, and that have been called out in an unstructured way in these forums.
Ones which come to mind right away are:-
Much faster load times
Greatly improved menu structure
Non-segregation of Premium and Standard cars
More tracks
Access to all cars with no requirement to "unlock" them
From what I've read, it is common practice for PD to evolve a game over time with free updates. I'm more used to the Forza experience where there is no significant functional evolution. I think I like the PD approach since it adds "freshness".
And while I'm on the subject of Forza and responsiveness to customer requests, ever since Forza 3, we have been clamoring for them to restore the ability to tune in the lobby. GT customers take this for granted, but imagine having to exit an online lobby just to tweak the brake balance. Then you have to be invited back in by the lobby owner, at which point, FM will pop you into the lobby, but in some randomly chosen car, not the one which you just tuned and therefore occupied. And for how long have Forza customers been asking for weather and time change? The list goes on and on and on. I posted a list of things which the FM forum users state have been dropped from FM5.
But back to GT6.
Looking at the big picture, GT6's potential release window arrived at a very "interesting" time. Close to the releases of both Xbox One and Forza Motorsport 5. And to add further "interest", it was close to the PS4 release date. Turn 10 couldn't afford to miss the Xbox One release date, and Forza devotees can see the result. Tracks, cars, functionality, all thrown off the release and the fans expect that when and if they return, they will be via paid DLC.
Likewise, GT6 was looking at a very finite launch window. To have delayed much beyond the FM5 release date would have allowed FM5 to enter the market unopposed, and sacrificed market presence.
I don't pretend to have any knowledge of the original GT6 content plan, however, it looks to me that PD had to make some hard decisions to prune GT5 functions out of GT6 due to the tight timeframe, while still retaining sufficient content and improvement to maintain competitiveness. They also had the PS3/PS4 platform decision to make beforehand.
I'm not at all surprised about the choices they made. Those choices and the "promises" of things to come such as triple-screen attracted me into GT (from FM1/2/3/4), and I'm more than satisfied with my decision.