Its weird how Gran Turismo used to be THE prolific racing game on consoles. And now its just another sim racer thrown onto the pile. The franchise needed a huge overhaul or direction change after Gran Turismo 5.
Something like a story mode would've been interesting. Starting as someone that races in city streets, moving onto racing at tracks where you can independently register or sign up, onto professional racing outright.
Or even a owner mode where you manage a racing team. Decide what vehicles to get for your team, which drivers to hire, pit crew/mechanics, competing for sponserships.
They kinda tried that with the B-Spec mode, but in the end it felt shallow and gimmicky, like pretty much all of the extraneous stuff in GT5. The problem with a "manager mode" is that GT was never a robust enough sim of actual motor competitions (licenced or imaginary) to really support it, IMHO.
For all the shit we gave GT, I'm not certain the core tenets of the franchise are so outdated. It has gotten a bit stale and tired, but there was no helping that once GT wasn't the only game in town anymore. I'm sure the franchise will continue to sell decently no matter what, if only by virtue of the PS4 leading the market...
Ultimately the loss of good will lies completely with Polyphony and just how warped its dev process seems to be : The car sounds still being a laughing stock after a decade of fan demands is one of the major examples and you'll find similar complaints about IA, damage model & collision physics, no livery editor, the absence of line starts & real qualifying or a solid online (though GT6 online mode apparently tried to adress those latter issues)... despite PD promises and the standard set by competition. Plus the scandalous asset disparity and planning management. But heh INSANE PHOTO MODE !