I've always felt that professional musicians make their true income by doing shows and mechandise distribution rather than making money off of the albums. The record company who mass produces and distributes the music gets the larger portion of the money made by album sales.
In my eyes, the only purpose of charging for the music is to pay off the record labels for promoting the band and the band's music. Well, except if you look at it from the record companys' point of view because they're in the music business to make money. Artists generally don't give a shit about the money they make from albums unless they produce enough to actually become greedy.
That's just my point of view, though. I'm a musician but not a professional musician.