Except I've been playing Forza 5, and they gave me $4M credits, and I bought all the expensive cars I could ever want during their half price sale. And frankly, I didn't feel that it was even necessary. I have been earning credits at what feels like the same rate as Forza 4.
I haven't felt encouraged to buy credits (tokens) at all.
In fact, Forza 5 is really generous since you don't even have to be in 1st place to win a Gold trophy for a lot of the races.
True, but the payouts are still quite small for earning gold. I don't have the difficulty boosted, so that has some impact, but i'm only seeing 5K per race. Which I think works for some of the earlier races with cheaper cars. But once you've purchased a Ferrari or Lambo the payouts should be going up so that you can earn faster. In my opinion at least.
I also hesitate to give them too much credit for the Forza Rewards. Sure its a huge help to get a huge chunk of credits like that, but its a bit weak that you have to browse their website to get to it rather than accessing it in game.