BM is really (too) simple though, it's braindead boring.
Now i'm not in favor of overcomplex "play the piano while playing a game" sorts of set ups either, but the space in between should be most heavily populated.
And more importantly: The piano shouldn't be close-to mandatory to be viable in the highest rungs.
That doesn't mean BM is anything clise to a gold standard either though. Just cutting the crap by cutting "press button to do unremarkable things" out of it could solve a lot for most classes.
"Slam" being my prime contender for such an ability (i mean i have it my sig for a reason, seriously that ability...), unless it gets consolidated into an earlier-mentioned "coat hanger" sort of ability that can be modified by talents into something actually interesting.