Daniel Waters (the screenwriter of Batman Returns) wasn't satisfied with Joker being kept alive at the end

https://diaboliquemagazine.com/episode-13-a-conversation-with-daniel-waters/

https://www.batman-online.com/forum/index.php?topic=3999.0

“I didn’t like the cavalier way that--that was not in my script--the cavalier way he blows up a clown and puts a bomb on him and throws him down a vent. I had some respect […] I don’t remember if I did have him kill anybody, but I was not against it. Like, I was a big proponent of you can’t have Batman wrap people in a mat and drop them off at the police station anymore. We don’t live in that world anymore. It doesn’t make sense. Like, I had no problem with Batman killing somebody. But I didn’t do it that cavalierly, I remember that. I have a good friend, Josh Olson, who’s also a screenwriter and wrote A History of Violence. But he’s a big Batman purist. […] He gave the greatest proclamation about Batman Returns. It holds true, as harsh as it is. That Batman Returns is a great movie for people who don’t like Batman […] Christopher Nolan has Joker hanging by a wire at the end of Dark Knight, and the Joker’s already proven he can escape out of any prison. Like, we’re supposed to think that’s a satisfying ending? I want some deaths. I don’t even forgive James Bond movies where they kill the villain off screen. I want to see the villain die.”