Who wins by restricting choice?

I was thinking..... A dangerous habit, but it happens from time to time. ...Thinking about online music, and 'personalised radio' in particular. That's sites that stream music to you based on the sort of music you like . It was prompted by a piece at the Digital Audio Insider on revenues from Lastfm - an interesting artists eye view of getting paid for putting music online.

Now on sites like Lastfm royalties get paid for each streamed play... Which means that if I like an artist it's in their interests that I can choose to play just that artist, and in the songwriters interests that I can play just that song. But what happens in practice is that what I get is a different artist playing a different song.. And the revenue I might have generated for an artist I like goes instead to someone I never really asked to listen to.

So who wins by not letting me choose?

Answers on a postcard please