Because enough people pay to watch the people that suck and not enough talent or musicality is paid attention to by "mainstream" anymore... pop anyway.
I find this station occasionally has decent music: http://www.wyep.org/
They have a live stream as well, even though I don't need it here. Because they are publicly supported and not owned by a corporation that owns artists and pushes those artists they play the good stuff that gets pushed off to the side. Now, there is some inconsistancy. I've turned on that station and heard gregorian monk chants, for instance or Irish folk tunes, or American Folk tunes, or really sweet guitar solos. I mean, you hear everything from blues, jazz, rock, folk, electronica possible on that station, and some of it isn't very good. But, its all better than the repetitive stuff I hear elsewhere.
I'd check to see if you have anything like this near you...