Last night, a non-gamer friend of me asked me what were the reasons for making violent games. I was stumped - partially, I admit, because I had previously drunk a bottle of wine. I could think of reasons why it's wrong to force people not to make violent games. I could think of why it was easier to use violence as a way to resolve conflicts. I could think of how people like transgression in play, which is one of the main reasons why the GTA and Tony Hawk series are so popular.
But that didn't really answer the question.
Update: by "violent" I mean "depicting or otherwise involving physical violence towards living creatures or approximations thereof".