I think giving a villain a realistic history (for them) can only be a good thing IMHO as not even villains see themselves as evil (unless they're crazy or Him..which is pretty much the same thing) and every character has a reason for being who they are and..well, not giving the villain an emotional history (since a lot of hate starts with emotional scarring) just to keep them 'the villain' can make them less of the character they could be :(..And in turn, it can rob the heros of the depth they could have by knowing/being a part of that history and how they react to it, like Professor X and a certain villain...
http://www.youtube.com/watch?v=BSh2zBGwCxw