One can only defeat so many villains that want to "cover the world in darkness" before one starts to look for a different flavor of horrible.
EVIL JUST GOT EMO!
Historicly, we have had plenty of rl groups like the Taliban and the Puritans who supressed anything which was in any way fun. What if there was some group that was the opposite? (which in time would cause problems of it's own for the civilians under their control.)