I will sincerely never understand the logic behind this reasoning. Personally, when in the realm of video games, "getting what I want when I want it" is not just reasonable, it's expected, provided it's not short-circuited with scummy tactics like paying more money to unlock it faster than everyone else. I am content spending money - once - to play a game and access what it has to offer immediately. If not, at least make the progression fun, not a work-like grind. I don't care to turn a video game into a second job. There's plenty of cars to drive, learn, and tune. That's enough "work" as it is, and driving and tuning as many as possible is - at least for me - the point of the game.
In short, if I'm gonna bust my backside doing something, I'd rather it be driving the cars and tuning them to perfection - you know, the point of a driving game?