skogenjake: I respectfully disagree with the part about mainstream being similar to the "underground" or "core" hip hop. To my ears, the "underground" stuff has more bite, it's more intense, has more intricate rhymes, etc. The mainstream stuff seems watered down to me, but again, that's just me.
To whoever: As far as punk goes, punk was an attitude and behavior of non-conformity (of various types: political, theological, etc.), hence my first post. It's become some trend, which is natural I think, so think of it what you will. Once people realize there's money to be made on something and they take the effort to popularize it, it generally loses at least some of its artistic credibility, IMO. And this is why I think the original concept of punk, in it's original form, is dead.
Are there still good punk bands? Sure. But that raw extremity of early punk can't be replicated, nor should it be.
Final point: Things (punk, for example) are meant to die. They change and alter and eventually the original concept gets forgotten. That just seems to be the way things work. It's not inherently wrong, it's just the way it is.
Tha's my two cents.