I think it can be easy to make cr at times in GT3, but you only really rake it in on the longer races in the Professional league. If they kept the prize cr similar to GT3 but have this thing where parts will waer over time and you have to pay to replace them it would balance it out.
As for RRRRRUL's comment, it kind of takes the point away when you get enough Cr early on to buy a car that will pretty much win the game for you. I can remember reading a guide for GT2 a while back, it started off ok up to when you get your third or foourth car, then it said win this race over and over and keep selling the car and you'll have enough cr to walk it the rest of the way, whats the point in that.