Taylor Swift can withhold her music from streaming services because she's a PHENOMENON who can still shift albums via iTunes (and even physically) because people want her music. Artists starting out don't have that luxury and, increasingly, their music won't get the listens if it's not on streaming services.
It strikes me as similar to the situation with people only buying games that are on Steam. Consumers love the convenience of a platform that is in many ways quite anti-creator. Tough one.