like wrangell said it does have some to do with whats popular and also it has to do with how its presented, and whose listening to it. lets use disturbed for instance. their song another way to die has a good message to it, stop pollution before its too late, now that message is only going to be heard by people who are into that kind of music. and then there's a slim chance that those few will be able to convince their friends/family, depending on the situation, that that "noise" their hearing is actually portraying such a thoughtful message. this is a really big topic to talk on but it all boils down to what music people like and which genera are portraying which messages.