Most radio listeners want their music on the radio. But not just that, they want talk, too. Otherwise, they would listen to their CDs. They want to feel part of an intelligent and/or funny and/or nice conversation, even if they're just listening.
Microsoft's cheeky playlist stripping (where you get just the music from a lot of stations) won't do it for most listeners, I suspect. What would be really interesting was to be allowed to combine any playlist with any talk between the records.
Some music-and-talk combos need to be live. Most morning shows do, as they combine music and small talk with current news and events. More topical shows are often made on tape, and could be on-demand.