Heatman
Hustle-Loyalty-Respect
Yeah, villains give another dimension to the game, or else there would be no fun if it all there were was good guys. The need to be beatable though, making them too hard to beat is always a concern.
The conflict that villains brings makes it more fun to play, there is no doubt about it because without them just as you pointed out, it would be one boring play that is filled with good guys or characters.