Blame the Christian majority, for one thing.
And secondly, I really can't see a song about Chanukah other than Sandler's. Hm.
"During this performance, please feel free to let your cell phones and pagers ring willy-nilly. However, do remember that there are heavily-armed knights on stage and you might well be dragged up and impaled."
(Pre-curtain announcement at the new Broadway musical Monty Python's Spamalot)