Well, that's the thing though, just like those who consider roof or chase cam to be "cheating" for some reason. This is meant to be a game for everyone. We all don't have 2000 hours a year we can devote to one single game, or gaming period. I sort of so, but I like to play a number of games. I also compose music write, and they require all kinds of time. Some people like me who have families or other time constraining things to deal with would be facing the prospect of spending years to get through the game. Many of them will want to race online, and don't want to wait six months to a year to join an A Class race with their friends.
This is why I agree with Kazunori's attitude, that having a car in Gran Turismo means owning the car, and it isn't yanked away from you when you get the next game in the series. As I said before, I'll transfer everything from Prologue, most likely, but go through the game essentially from the beginning, as if I haven't transferred a thing. If others can't or won't do that, it won't affect how I make my way through GT5 one bit. However, I will have a range of cars suited to various race classes when the guys from here want to do some online racing.