Because they didn’t use source material as they should have this movie fell flat in my opinion.
They made it completely about Batman and Catwoman using the material from the recent story arc of Batman/Catwoman wedding.
You actually could have made a second movie-
The Batman/Catwoman wedding
But instead they butcher a BEAUTIFUL story by Loeb/Lee. Just like they did with the Killing Joke. Which was $#it on toast, that butchered Moore’s work. Using a stupid underlying story of a Batman/Batgirl relationship.
I’m starting to lose respect for the Dc animated movies. I hope they do a better job with Wonder Woman bloodlines.