I get my music recommendations from music blogs or my local record store, and I always always always find them more relevant than anything an algorithm poops out. Finding a way to scale that up would be interesting, but I also don't really think that there's a lot of money in it. Google could do this, really, or Facebook, I suppose, because they have the huge amount of activity data that could be used to take the place of "Hey, I like this Galactic Cannibal record, what else should I be listening to?"
Just because no one has done it really well yet, that doesn't mean we should all go back to human-curated playlists in my opinion.
Edit to add: Perhaps part of my reluctance to rely on DJ's and human-curated playlists is a lack of trust. When a person recommends something to the masses, my gut instinct is to question motives (who is being promoted and why). When an algorithm recommends something to me as part of an unlimited service, I tend to feel like it's been tailored to me for no reason other than to maximize my enjoyment (though admittedly, the truth is that algorithms may be built with just as much - if not more - questionable bias as any human).