Because I don't think we fit into the cultures we live in. Nerdy we may be, but gaming has always kept an element of the counterculture. Wasting your time in another world playing games is as counter to mainstream thought as grinding rails all day at a skate park. Gamers exist as a force of intelligent young people, and to some extent as a force of counterculture. We gather online and off and discuss things that Joe Smith just wouldn't get. Not even Hollywood gets us, as nerdy film students depict games as button mashing drool-inducers. We are segregated by enough of a margin from the loafer-and-tie white collar worker of the mainstream that I think some educated assertions can be made.
Whether it be a game themed around the apocalypse or not, all videogames represent the breakdown of the society we live in and the virtual construction of another in which we can start fresh as the people we really are - or want to be.
In Jane McGonigal's TED talk, she asserts that videogames bring out the best in us; in World of Warcraft we come together, we assist others and proactively attack the world together. We form clans that game together and establish online relationships with those people. Whether we want to admit to escapism or not, we are actively seeking a second chance at being ourselves.
Benjamin Nugent suggests in American Nerd: The Story of My People that the nerd, or at least the (not unreal) stereotype of the nerd, has a lot to do with describing people of the introverted and socially downtrodden variety - not just the smart.
He describes friends from broken homes with whom he shared deep gaming moments, moments that allowed them all to escape and be strong. He interviews friends, now nerdy adults that he left behind when, at that point we all come to in life, he decided to become a "normal person." Nugent left them behind and conformed to society; he got a girlfriend, dressed normally, did well in school. He regrets that.
I tried to grow out of it too. I started playing football. But I found myself talking to the poor kids on the team about Grand Theft Auto and Halo. I was not bad at the sport, and I enjoyed it most of the time. But it was part of a world that I knew I didn't truly want to participate in. If I was going to escape into a world, the muddy football field where I wasn't allowed to swear but was rewarded for tackling people - that wasn't where I wanted to escape to. To become a jock meant leaving behind all the things that made me, and I couldn't do it. So I escaped from there, too. From that point on I embraced the nerd in me.