But I'm guessing that a lot of these devs are really interested in x genre, but they're working in y genre, so why do they take the abuse? Is there just a huge over supply of game devs?
Bingo. Too many people think being good at playing games means they are good at making games.
Edit: Although QA probably gets treated the worst, and many programmers/designers use QA as a way to get their foot in the door.