Where the whole population is addicted and governors risk their political career to ban the addiction, and then get their territory invaded by the corporations they kicked out who have returned with a foreign military and mercenary army, to push the addiction back on the populace
Actually sounds like a not so bad setting for a book/game/movie ngl; sure sounds like a garbage setting for a world to actually live in.
The nicest looking one I could find was amberol, but that was a bit too minimalistic for me. I like minimal UIs but that doesn't have to translate to minimal feature sets as well.
But in the end I didn't find any simple but hackable players that I liked; in the end I just settled on audacious because it's just simple enough in terms of UI and good enough in terms of features. I do like the playlists as tabs idea though.