Which is structured around the idea of you racing to earn money to buy cars. It'd be like wanting to PLAY the GAME of football/soccer but complaining because you can't touch the ball with your hands. The amount of money you've spent is irrelevant: this kind of experience's what you paid for, you don't like it? Shame's on you for dumping money on it in the first place.
That's the kind of attitude that makes the "whining and crying" thread undeservedly one of the most popular in the GT (or in any other game's forums) section; the idea that as a paying customer you get any say in the basic philosophy of the product, a weird phenomena that reached its peak with the "retake Mass Effect" movement but is strong in any community. No, you're just entitled to pretend it works as expected and to decide whenever it's worth the money for you or not.
And before you come at me saying this is a "legitimate complaint": no, it isn't. Complaining about the several annoying glitches is. Wondering why for the love of all that's holy they removed photo locations that were more detailed than those that we have now, for example, would be legitimate. But this I can't accept as "legitimate". There's plenty of games out there that don't ask you to WORK to earn credits; GT always worked this way, and will likely keep working this way forever.