Maybe this is ridiculous, but why not have multiple ways of doing playlists? A .playlist file for static (or smart) playlists that gets parsed at startup and turn into whatever sql fu necessary to create playlists. Then, a web based way of managing playlists more on-the-fly so to say, so that you can create whatever mix you happen to want to hear at that exact moment.
I realize that it’s more work than choosing one or the other, but it would also be the best of both worlds…