I played GT3/GT4 on PS2, I also played other racing series on PS2 such as Toca Race Driver, F1, WRC, Colin McRae, NFS, Burnout, Midnight Club, and the Forza & PRG games on the original Xbox.Have all the people who are vouching for 'All Cars Available At The Start' played let's say any of the PS1 and/or PS2 GT titles?
Grinding to unlock stuff wasn't as bad back then because I didn't have a full time job and bills to pay and had a lot more free time than I have today, but the whole "grind to unlock stuff" process got old after a while.
Nowadays I'd rather spend my time racing, not grinding. That's one of the things I love about the F1 & WRC games, they have a career mode where one can start from the bottom and work their way up, but it's optional, I can simply skip that and do custom races/championships with whatever car/track I like.
I don't mind PD keeping the traditional GT mode in future GT games but ideally they should add alternate ways for people to play the game and access all the content the game has to offer.