> You want to write a song, go write on, you don't need to mix someone else's.

Why I don't generally like bringing up fiction as proof of my words, Melancholy Elephants story has a very clear and explicit answer why this is a bad idea: http://www.spiderrobinson.com/melancholyelephants.html

On top of the examples already in the story: Disney's empire is built directly on the back of directly using public domain works or remixing existing works. And yet, you want to prevent anyone from doing just that.