Read the last paragraph.
People remember athletes for their achievements, and sometimes antics. Take Alex Ovechkin for example. Sure, he's a good hockey player. But some know him for bringing the "touchdown dance" to hockey, and sports channels have picked up on that. Now, consider someone like Barry Sanders. Ever notice what he did after getting a touchdown? The Back or Field Judge received the ball, and the game went on. Now, let's consider RPI/Union at the TUC last year. People don't talk about RPI winning. They talk about the hissy-fit fight thrown after the game.
The point is that character and class don't happen very often because a lack of it sells. Why show character and class when you aren't going to get much out of it? People go for the "sucks" chants because it gives them a temporary resolve of positive emotion via the Law of Disjunctive Inference. They could care less how other "tribes" view them, so long as they believe that their "tribe" is better than another.