In talking to most of these bands, they are happy you hear of them through downloading MP3's. Most of these bands can't do it for a living, they have regular jobs so they just want their music out there. And every once in a while a band gets enough exposure that can do it for a living. But the only way to get that exposure in through the internet. Hell, you ask any metal band how they found their musical influences and how they find new bands, they'll all tell you they downloaded the music.
which is why I'm starting to love my university (university of Saskatchewan, top end physics and comp sci), my computer science department spent a couple years investigating the most successful teaching programs in the field. They wrote their own textbook but just did it in pdfs for us to either print or download or just read online. They told us to return our textbooks (required on the main website to put a textbook). Also my linear algebra prof said any textbook will do, she hates the one the department uses anyway. Tons of books in the library so I just use that. Last, my classics prof said we can use open domain translations as long as we cite the material.
I saved a ton on textbooks this year, only needed one physics book.