They should've just done the Batman Animated and Superman animated crossover for the whole concept of the story. Not stupid 1 vs 1 fight, it was just Batman following the trail of joker who stole an expensive artifact from the Gotham museum which is made out of kryptonite and he went to Metropolis to make a deal with Luthor. Bats ended up confronting supes for like 5 seconds and got his ass handed to him but it eventually showed how both of these characters were different yet came together to fight for a common goal. Straightforward story no convuluted bull crap, no extra things added in they kept it just to Metropolis. WB would have probably even made more $$$ on this movie had they done this instead with both Joker and Lex the 2 most well known villains on the big screen facing the 2 most well known heroes.