Out of extreme curiosity, how do all if those music apps in the store that allow limitless streaming and downloading of music not get pulled? Isn't that illegal???
I suspect MS is taking a slightly laid-back approach, feeling it's not up to them to police who's making what available for streaming (perhaps, naively, assuming they're all legit).
And those services have to have some kind of income, be it from ads (displayed or audio) or by selling on user information. Or quite likely, both. I doubt much revenue reaches the artists.