i never quite understood the concept of a word being bad. it's just kind of dumb to me :I but people use them in place of expressing things because they're easier to say i guess. i sometimes just say them out of frustration, but that's what happens when you're a gamer :)
Profanity is the recourse of a weak mind. People can't argue a point intelligently, so they spew profanities instead. I think it also depends on how they were raised and who they socialize with. It just becomes part of their everyday language. I don't think they realize how poorly it reflects on them.
It is called 'bad words' because the words are not meant to bring the person being told any good. The words are like wishing the person bad luck. Most of the people use them when they are irritated even if they don't really mean it to happen as they say.