Holy Musical Batman/Headscratchers

• So, why did they kill off the Joker - offstage, and before the show even really starts, no less - just to replace him with a character who's exactly the same with the addition of candy-related puns? Heck, they even gave him a Harley Quinn expy as well. Not that I'm complaining as I loved how it was done, but it's really weird to me that they did that instead of just using the Joker (considering how popular Mr. J is).