Yeah I think you're getting a bit mixed up here Nick.
It's the publishers who have all the money counters, and they're the ones who are responsible for saying "The first sold like crazy, so let's make another!".
The developers are the ones who actually make the game and get paid roughly the same whether it succeeds or fails, so whether or not the game is a true labour of love is completely up to them and how motivated they are.
Developers usually aren't random guys who don't give a damn. They're people whose living is making games, and like anybody they want to do something they can be proud of. It's not in their interests to spend a year or two making a cack game; the only reason this happens is if the developers are given a really lame project, which does happen sometimes and is the only way for a studio to get assigned some juicier projects later on.
Try to remember that you're talking about people and not robots here, heh.