What exactly is "selling out"? Do people actually think that if the band can pay their rent and afford to get a cavity filled, if needed, that they're suddenly going to start making crappy music? It's not like we live in a time when there is a distinct line between mainstream and alternative music scenes. That was the days of your parents and grandparents. The world is way more jumbled up than it used to be. Nowadays it's perfectly normal to have tattoos, piercings, dyed hair, etc.-- all the old trappings of not "selling out". Present-day senior citizens rock out to punk because they were there when the s**t was invented.
Now that music has been digitalized, it's accessible (and thereby possible to be appreciated) to everyone the world over. Gone are the days when you had to get to the one record store that actually sold the unknown band you were cool enough to know about. Gone are the days when the only kids that had access to good music were in a handful of big cities . Today, you can download anything you want, from anywhere you want, read up on music anytime day or night, learn about the most obscure things. The world is as accessible to a kid in Handan, China as it is to you. It used to be that people complained that mainstream music was crap. Now good music has gone mainstream. Sure, there's still crap out there, but the good stuff is more accessible. We may have lost the ability to feel superior over one another for being more in the know, but we've gained a world where a goddamned amazing songwriter doesn't necessarily have to choose between making the music he or she loves and putting food on the table.