1) Currently file sharing focuses on consuming content, not creating it, and usually it's facilitated by people who's only objective is to profiteer from copyright infringement rather than any greater good.

2) Those companies pay royalties for the music you listen to. Some arguably insulting portion of that revenue goes or is supposed to go to the artists. When you go to TPB and view a bunch of ads and popups and shit you are only paying the site owners.