Annonymous

I think that the annonymous factor allows people to lose fear of judgement that so many of us often face in our day to day lives. I think that your character is an extention of oneself. Therefore they are annonymous to the other players (unless you're playing with friends) and that you can include as much or as little information in your profile as you choose.

A lot of games allow you to name your character i've noticed or to take on a specific character thus revealing very little about the identity of the person who is controlling that character. For all you know knight5201 could be a 80 year old grandfather or a 12 year old school boy. I think that the world of gaming allows the opportunity to submerse yourself as publicly or as annonymously as possible. Even though you are intereacting with others in MMO's you still control to the degree of participation you involve yourself.

MMO's offer socialization and allow interaction with others whether it be collectively to try to accomplish a mission or whether its purely for social chatter while playing the game. Perhaps for some people this is where they feel most comfortable socially and feel accepted by fellow players. Perhaps it allows them to express themselves in ways that they cannot in their everyday life.
I think in that aspect annonyminity is a really great aspect of the gaming world.