PD don't have to do anything. They are a company that makes games for entertainment purposes and they do that, very well. If they listen to us GT fans, it's because they value our input and opinions.
But everyone that plays Gran Turismo has different opinions about how to improve it. So they have to be selective about what they "tinker" with, as it all costs them money.
I pre-ordered the Anniversary edition and the chap in the store told me it came with the Apex 2 booklet. Which it didn't, in the UK. I also thought it would have B Spec and a course creator, which it doesn't (yet).
In time, I believe that GT 6 could be a great game. But it's not there yet.