What kind of adjustable parameters? I'll admit I'm intrigued by the prospect of songs that vary slightly on each play-through (e.g. slightly different drum fills, different solos, etc), but I suspect this is distinct from what you're suggesting.

I'm also of the belief that piracy of digital arts is largely a cultural thing & that attempts to prevent it by force will never be more than marginally successful at best. That said, I have zero evidence to back it up. It's something I'd like to investigate, but I don't know how.