In my opinion this is happening because of the fact that gaming is becoming more and more mainstream, so people who are used only to talking to people in real life, where trolling and being mean usually caries serious repercussions, are suddenly getting hit by the internet culture where trolling and being mean is just part of the culture in general and they don't really know how to deal with it because they never really had to.

Great post! Would you mind if I included it in today's "best of gaming"?