They had the perfect set up with the end of Man of Steel. All you had to do was pick whether or not Batman was the protagonist or antagonist of this new story and you had your movie. Imagine if Cavill got to really spread his wings and show some character and charisma instead of having to be a moody, boring, monotone Super-***** that's only there to die? Superman is a great character, the embodiment of wish fulfillment. You like MoS don't ya? Remember how cocky and sure of himself he was at the end with the satellite drones and ****? He actually smiles at the end of movie! Instead of opening BvS with this weird, depressing Superman that's going to the Middle East shoving terrorists through walls and acting all bummed out because he still doesn't know his place in the world, you could have had an alpha Chad bro that flexed his muscles for the world to see. I'm not talking full Reeve here, just a natural progression from MoS. Instead of sulking and calling his mommy for advice, he could have flew directly into those interviews and news segments to join in on the discussion about "why Superman is bad" and prove them wrong. Imagine him pushing his cape back and sitting in on those dumb Charlie Rose or Neil Degrasse Tyson interviews and shooting down everyone of those arguments with points about how he's making the world better. This guy can literally do whatever he wants and he doesn't even try to defend himself? He's the most powerful being in the world and is banging Amy Adams, he shouldn't be brooding. Certainly not the extent he does in BvS. You could have had him flying around the nation (and world) going out of his way to positively change the public perception of him for the better. Maybe he gets too arrogant or loves the attention too much as more and more people start to love him (remember that army chick getting all wet for him in MoS) and he becomes this media/PR sensation. Maybe he starts actively working with the government to prove to everyone he's on the same team, maybe he vows to rid of all crime and corruption for good . . .
All while this is happening, you have little beta Bruce watching all of these news reels from the shadows underneath his lonely Manor. Nobody likes Batman, he's a ****ing weirdo. He never really improves anything, he just keep sending psychopaths to an asylum with a revolving door and getting people killed. Alfred is worrying about him, he seems too far gone after the events of Man of Steel. Batman was obsessive already, but with the likes of someone like Superman entering his world? That's earth shattering. Superman's very existence threatens Bruce Wayne's world because if there is no long crime, Batman has no reason to exist. Deep down, he knows this. Even that stupid Lego movie understood this. Batman can be a damaged character. Instead using his wealth for the betterment of society, he uses it to ****ing making gadgets and toys like a child. Schumacher and Nolan already gave audiences a super heroic Batman. You could have easily doubled down on a bitter anti-hero that fears everything Superman represents. Hell, it doesn't even have to be a fear of what Superman is capable of, maybe Batman is just jealous of him because he can NEVER be those things that Superman represents. Maybe it gets to a point where it's like Batman's services are no longer needed with Superman and Superman is basically like "look, I know who you are. You're not needed anymore. I got this. If they shine your light in the sky, you don't need to go to it. You're done buddy boy. If you put on the mask again and do this vigilante ****, I'm kicking your *** and taking you to the authorities" effectively shutting him down. Bruce can't cope with this because he needs Batman for catharsis and therapy he snaps. He schemes and plots to bring Superman down, effectively becoming the villain of the piece. He looks into his weaknesses, builds himself up. Creates the armor suit, synthesizes the kryptonite. Then when he goes to the batsignal and puts that **** on with that little grin, he's doing it out of real contempt and mockery for Superman instead of some weird contrived Lex Luthor plan where he tricks Superman and Batman into fighting one another. It could literally just boil down to Batman having a death wish. This isn't the Nolan Bruce Wayne that's looking to retire and move to Italy, this is a Bruce Wayne that made a weird, candle lit vow to avenge his parents' death by all means necessary. If he has no purpose, he'll either take Superman out, or die trying. Maybe you have Superman and Batman learn something about themselves, through each other.
Instead we got some weird half baked political thriller with Wonder Woman and the cave troll from LOTR thrown int. Bad ****.
