Who knows what evil lurks in the hearts of men (and women ... and children)? Certainly most MMO players, or to be even more general most people who go on the internet know at least what they expect other people to act like. Certainly they would act like normal people right? Upstanding citizens, keeping the peace, helping old ladies across the street, buying girl guide cookies. But then if you have those fine folks, you certainly would have to have their counterparts, the criminals and scum-bags of the virtual worlds, preying on the innocent and weak. A sort of symbiosis has to exist even online, else you would either have complete anarchy, or pure utopia (and that sort of thing could never happen in a video game, eh Jack?) and neither of those situations truly juxtapose reality, they simply.
And that's what MMO's are supposed to do in some sense or another if I'm to believe what all the articles, thesis's, and marketing materials say. Even in the trailer for the upcoming MMO documentary Second Skin they say things along those lines. So you have to balance the good with the bad to have a virtualisation with reality, but then something is amiss, because it's certainly damned hard to be a bad guy online. Oh sure you can gank people in PvP, or use MPK tactics to train monsters on to groups, but those sorts of things make more of a dickwad than they do a truly evil person.
Something I hear flying around a lot these days, mostly in conjunction with RIchard Garriott's sci-fi MMO Tabula Rasa, is the idea of morality. But can there really be moral choices in an online world, where just about everything a character does is pre-destined, set on rails, and left to run its course on its own time table?