From my experiences with MMORPGs and people in general, when there is challenge and struggle, people come together to overcome that. And when there is very little, people tend to do their own thing.

It just seems like on a place like the internet, where anonymity is an impregnable shield people don't feel the need to be pleasant or kind to others, because there is no risk of reprisal. You can hide anyone you don't like, and the community is so large that there's little risk of you earning a name for yourself, neither positively or negatively.

There are some good ones still, but they're hidden in the brush and few and far between.