It's not that going mainstream makes music bad, it's that music that's apt to become mainstream is, by necessity, likely to be bland. It's music that appeals to as wide an audience as possible, and as such ends up chock full of proven elements that no one can hate. In other words, a bunch of stuff we've all heard before that doesn't inspire one to think and engage.
It's the difference between fast food burgers and a bleu cheese sirloin patty at a steakhouse. Between Olive Garden and the family run Italian place on the corner. I can appreciate a Carl's Jr. burger on occasion. McDonalds and Olive Garden can go screw. And hey, there's even the occasional standout like In-n-Out that manage to both have popular appeal AND retain a healthy dose of uniqueness. But I'll take that sirloin patty over that whenever I can.
And right now, that patty is in the form of the decadent resurgence of psych rock. It was off my radar when it seems to have began back in the late 90s, but now that I've been clued in, I can't get enough of it. But if one more person hears me say that and recommends the New Pornographers I'm going to puke.
Some people want to run off and join the circus. I want to run off and join the Elephant 6 Collective.