It is particulary important to pay for music for the "unpopular" styles of music. Folk, jazz, classical, etc. are tiny portions of the music industry and they really are struggling to surive as a viable business model.There are musicians that *hope* that their latest cd will sell 5,000 or 10,000 copies. At those numbers every single sale is important.
It just wouldn't be right not to pay after they put their heart and soul into their music.