redlemon:
From my view point it's all part of the experience. It's adds a certain something to the song and the concert. It's also about the aggression of a song. You can get out your aggression in a healthy manner and be respected and respect those who feel the same way. It's also a kind of "rite of passage" at some concerts. Think about it this way: You go see Hatebreed and the song is kicking your ass. How can you express that beyond screaming and giving devil horns? You mosh your ass off that's how.