I think part of the reason I am kind of glad this movie got slapped down so hard is that Warner is trying so hard to be Disney/ Marvel while trying to appear as something completely different, or show they're the more "mature" franchise to try and bleed Marvel fans. The whole thing just seems cynical, and it's hard to put a finger on why. Maybe it's that they tried to make 1 movie out of 3, or that Zack Snyder is a hack director, or the movies appear to be trying so hard to be anything but fun, it doesn't seem like anyone really cares about the characters or the source materials.
See, I'm going to disagree, but
only because I know what
could be done as a writer.
Comparing Marvel and DC is a bit... Unfair? Marvel's heroes have always been more about expressing experiences within humanity. The X-Men for instance are mostly just a collection of discrimination stories featuring the humanity of each protagonist, and how they deal with it. Some are colder, some are warmer. Some are smarter, some are dumber. Some are better able to deal with the intolerance that society shows them than others, and their powers often reflect part of their nature. Wolverine has claws because he's a berserker at heart.
DC's heroes on the other hand have always been more about the ideological conflicts present within each. Superman is an immigrant, but the forefront of his character is and always has been his unfaltering idealism and faith in humanity, and his adoration of rights and freedoms and the sanctity of human life.
If DC and Marvel were university degrees, Marvel would be the psychology major, and DC would be the political sciences major.
You can even see hints of this in their movies. Marvel's stories are 9/10 times the hero's journey arc. They have an established flawed character at the beginning who has to overcome a series of obstacles and discover his powers and/or gadgets in order to win the day. The plot for Antman is the same plot as in Ironman, and most everything inbetween.
DC's issue is I don't think they understand how to write a dark universe,
or really understand the characters they're using, and how to port them properly to the big screen. As flawed as Man of Steel was, you can make a dozen arguments defending it. Superman obliterates a significant chunk of Metropolis? He was still a newbie superhero and he was fighting villains who
intentionally forced him into populated areas. He doesn't understand the true destructive nature of his powers yet. Et cetera.
This new movie
has no excuse for why it somehow lacks humanity or an intelligent script. If you want to write a conflict between Batman and Superman? It has to be a political confrontation, because imagining the two hitting each other "just because they don't like each other" is about as warped and beyond the pale as it gets for those two. You can write incredibly dark and macabre universes, but in order for anyone to remain invested, you have to have likable protagonists. In order for a protagonist to be likable we have to grasp their motivation, and understand the conflict that they're in is somehow unavoidable. The only way they managed to do that was to make Batman into a mass murdering sociopath who runs people down and blows them up with cannons n' shit. That doesn't make him likable: That makes him a lunatic.
Ironically? This movie would have been far, far better off if they had just constrained the narrative to superman's cult following. Those who believed in him, and those who were terrified of him, and the political ramifications and consequences that comes with having a massive cult following
who may try to imitate the things you do. Superman would be forced into the darker but more realistic situation that his every action is going to have consequences upon impressionable minds. Batman could largely keep the same motivation he had before, but instead of being manipulated by Lex Luthor (because
that fucking plot arc was stupid) he could have simply seen a pseudo-God who obliterates entire city blocks whenever he engages in combat.
That alone could be enough to put Batman on the defensive and force a political confrontation that could result in a fight which lasts a solid 20 minutes and ends with the two in a draw, with one or both ideologically compromising and growing as characters. Atop this, you could keep and expand upon the two attempting to investigate each other: Superman under cover as the reporter, Batman under cover as the philanthropist billionaire.
You could actually have an extremely thought provoking, dark character study with these two, contrast them, and it's not
really that difficult to think of a reason for the two to be engaged in a conflict when they barely know each other.
Frank Miller grasped this in his own comic. Superman sides with the government, Batman does not. Batman engages in conflicts, it reawakens his old arch nemesis: The Joker, who goes on a killing spree. Batman's actions had consequences in bringing back the interest of his arch rival and it cost human lives as a result. Superman and Batman then had an ideological conflict that forced them on opposite sides of the spectrum.
The irony is that this film
painfully fucking obviously took cues from Frank Miller's comic, but the writer/director
somehow missed this core, important aspect of
why this comic worked.
Why people liked it. It was ideological as much as it was about the titular characters.
But no. Warner had to blow their load and shove Wonder Woman and Lex Luthor and others in there, who really didn't actually need to be there. What was Lex Luthor's motivation? What was Wonder Woman's motivation?
They really didn't actually need to be in this plot. Hell, the resolution to the conflict could have been that superman and batman start to cooperate more and become the baby daddies for the Justice League, and each follow up film would introduce Wonder Woman, Aquaman, and how they get involved in the Justice League.
Why the fuck am I better at this than the guy directing this multimillion dollar movie? I shouldn't be. I normally see a flawed movie and think "oh, well, I wouldn't have done much better." In this case though? For once? Yeah. Actually, I probably could have done better.
And that's really sad.
Because Marvel needs a genuine competitor to keep them on their toes so they'll stop being fucking lazy with their plot line. (Aside from the Avengers and Guardians of the Galaxy. Those film franchises are still neat in their own rights.)
EDIT
TL;DR: You could absolutely do a dark and gritty story featuring Superman and Batman. It's been done before. The issue is you need them to be likable, you need the conflict to be coherent and zeroed in on a single overriding plot thread, and that plot thread needs to be ideological to truly reflect the nature of these characters. Instead, the plot was overloaded with characters who didn't need to be there, and set-ups to future films that didn't need the assistance.