I agree, specially recently. The show started very nicely. Then with all these similar jokes and stereotypes that has been abused by the writers, it just got so boring. I like south park more, I find it smarter than FG.
That's an easy one. Too many people striving to be better fans and be better than fanboys coupled with the human nature to be a social creature. We want to be liked, to get attention, have power, etc. Humans want to stand for something, but at the same time be part of a crowd. These inhibitions tend to manifest themselves in this setting because the social consequences are not as harsh as the real world.
The better question is "why don't we attempt to get along"?