That's a fantastic idea. At the very least it would cut down on all of the "what song is in this edit?" threads, which don't come up all that often, but they could be prevented.
there is only one problem with that. many of us use a remix or a not know version of the song, so when the song plays it will not know what it is... youtube knows just because of the video no one tells them the song and they are mostly just mainstream or known artists.