Does it matter if something is "mainstream?" Really?

[Marching Band no Jutsu]

One of my "friends" (he's cool sometimes but other times I hate him) is a self-proclaimed "metalhead." (He likes emo music, by which I mean the crappy kind, and he likes Cannibal Corpse. That's the only metal he likes anymore.)
So, he used to listen to Metallica. Then, it got "mainstream."

Then he moved to Disturbed (which I like a lot) and gave me some CD's and was all over them. Then, they got "mainstream." (He judges whether something is mainstream by whether a preppy kid who listens to Underoath listens to something or not.)

He completely pushed Slipknot aside (I suggested it to him) and he won't even consider System of a Down or Bullet for my Valentine.

All he likes now is Cannibal Corpse. I asked him what would happen if Cannibal Corpse became mainstream, and he said that he would die.

This kid is also a self-called "emo kid," he wears eyeliner, dates ugly chicks and calls them hot, and calls hot chicks ugly. (We think he's just gay.)

So, this brings me to the question: Does it really even matter if something is mainstream or not? If it's good music, it's good music.  

[OoPeroxidePrincessoO]

Depends how "mainstream" it is. If they over do everything about it, theres a good chance I'll get annoyed with it.  

[Art Payment]

Marching Band no Jutsu

All he likes now is Cannibal Corpse. I asked him what would happen if Cannibal Corpse became mainstream, and he said that he would die.

I lol'd seeing how well known they are, ******** were in Ace Ventura Pet Detective in the bar scene.

I mostly listen to stuff that isn't mainstream, but only because what is mainstream happens to be pop rock, nu metal, post grunge, or crunk rap.