They gave Superman to an admirer of the works of Ayn Rand and ended up with an interpretation of the character that just didn't fit.
The Kents are supposed to teach Clark that he should use his abilities to help people, and that's the reason he has his gifts. Instead we get movies where both Kents try to convince Clark to not help people, and to be selfish.
It has a Superman that looks like he hates every moment where he's helping people, which is the complete opposite of what Superman should be.
Then they rushed to team-ups in BvS, and proceeded to more or less cut Superman's entire story line in the theatrical cut to the point that it feels more like a Batman film that stars Superman as the antagonist, and more or less robs Superman's death of any impact because he's acting like an asshole for most of the film.
Then comes Justice League, and rather than reacting to the negative reaction to BvS they push forward because the execs need their bonuses. But they do panic enough to cut the story of the movie in half and possibly boot Snyder off the film at the eleventh hour because he's making it too dark, bringing Whedon in and making the whole film feel schizophrenic. It doesn't help that the main villain is forgettable beyond belief and is defeated almost single-handedly by Superman, thus questioning why they needed a whole team.
There's also Suicide Squad which was another case of them not understanding the characters, because they take street-level villains and for whatever reason throw them into a super-powered threat situation along with soldiers, thus begging the question again why they even needed the squad.
So basically, they kept forcing characters into films where they didn't fit. They just don't understand them. The films where they get closer to understanding them work a lot better (Wonder Woman, Aquaman, Shazam).
