Maybe in the solo, we'll get some more insight into Batman's psyche previous to the incarnation we start with in BvS. I like to think he started out waging his war with the best of intentions, a strict no kill policy. I bet his early story is similar to the one told in the Nolan movies. He probably saw Harvey Dent as the incorruptible good who turned evil through loss and pain, and that gave him serious trust issues, that "eventually, you live long enough to see yourself become the villain".
He held to his standards and kept Joker alive, only to see him murder Robin, somebody who trusted Bruce implicitly, and maybe paralyze Barbara, idk. But can you imagine what that feels like? HaHa The Jokes On You Batman. He keeps that suit to remind him of his failure, that he is responsible for letting the scum of the earth win. He has lost all faith in his mission, so if a few criminals have to die, it's no big deal, people die every single day, we all have to die, he lives by the exact same principle that all soldiers do, better it be someone who has chosen their side than an innocent. If somebody has to die in his pursuit to stop a being that can destroy the planet, it's an acceptable casualty of war. Batfleck looks at Superman the same way Baleman looks at that atomic bomb. "Not cool with the no guns policy? Band's a goner, Talia got marked, not gonna save Ras, no big deal, it's for the greater good."
I like that this Batman picks up after facing the same questions that the Nolan Batman had to face. Though it's not the same universe, it feels like a continuation of that same story. The difference is, this Batman isn't going to quit or stay holed up in Wayne Manor, because his obsession has taken him too far. He's gonna keep doing it, criminals are like weeds, some of them are going to die, until he himself dies.
Superman represents Hope in the midst of darkness. He shouldn't be just a fun character, with some action, one liners, an absolute moral lesson at the end, and everything is okay. What the hell does the American Way even mean anymore? People suffer all over the world so that we can live comfortable lives, gas in our car, convenience, aww he just proposed with a diamond ring, our materialistic lifestyle has far reaching consequences, but God is on our side, so it's okay. That doesn't make us bad, by nature, unless we are willing to turn a blind eye to it. Superman is about not turning a blind eye, making the tough choices, he represents the best in humanity, as he should because he is the mythology of our modern age. He is what we should all aspire towards.
"They will stumble and fall, but they will join you in the sun" is the dream of Superman. I don't think, as a storyteller, you can effectively convey that idea without setting Superman in a dark, realistic world, show him as conflicted, show him having to make the tough choices. Real heroes, like the people who took back over that flight on 9/11, killed the terrorists, and crashed into the ground, sacrificing their lives and many others, to save countless more lives, they had to make the hard choice, and they represent the best of us.
I think it was necessary to the themes of the story to portray Batman as dark, broken, and cynical and have Superman be the one to bring him back from the darkness to his initial ideals. We can debate all day whether they did a good job telling that story, some liked it, some didn't, but it's a little unfair to say this isn't how Superman/Batman should be portrayed. Just like the Marvel characters, these characters belong to all of us, I grew up on Superman and Batman since before I even have memories, and I'm not gonna have somebody who read a couple TPBs, saw some cartoons and movies, tell me their idea of Superman is any more valid than the kind of Superman story that I want to see. Marvel's great, enjoy that, but let those of us who want a different story enjoy DC.