I came to this conclusion myself about 6 months ago, after Dalton Caldwell spoke at a YC dinner. I realized it was basically hopeless to start startups that touch label music, because even the ones that seem to be succeeding (in the sense of not being sued out of existence) are only allowed to live so the labels can suck investors' money through them. But by creating a startup-free zone around themselves, all the lab…
What PG says is 100% true. I say this having done a startup in the space. In a nut shell, you need roughly $1M upfront for legal fees to negotiate with the big four record labels (for an interactive service, not a non-interactive service like Pandora).
I guess I understand what you mean. Though I wouldn't use the words interactive/non-interactive. Pandora is quite interactive in a UI sense, even though you can't select tracks directly.