And yet somehow Superman comics have continued to sell for decades. One problem is that most writers/film makers only look to Donner's version, and don't really consult the comics. Donner's version - as fast as the Flash and as strong or weak as the plot requires - is hard to write. However, the fact that many stories have done it I think proves it's not as hard as some writers initially suppose.
From an action standpoint, Superman is somewhat challenging, but so are all flying, super-strong characters. In that regard I do think adapting anime fighting convention was a good move on Snyder's part. We'd do well to keep in mind that most of the credible criticisms of this Superman have not focused on the action, but on the characterization. And in that regard, Superman is not hard to write.
I've long believed that the challenge in writing good Superman stories isn't that he's too powerful or too perfect, but that he doesnt have enough around him to make for interesting stories. I think it's useful to compare Superman with Batman. Yes, Batman is a darker character, and therefore inherently a bigger draw, but Wonder Woman and MCU films prove that lighter characters can also draw a crowd. Superman has also been just as complex a character as Batman (as BvS tried to show), and so that isn't it either. No, I think what makes the difference is the richness of Batman's environment, the complexity of Batman's opposition (both personal and thematic), and the prevalence of multiple supporting heroes, villains and civilians that together embody the complexity of human experience.
Broadly speaking, Superman lacks this comprehensive development, and it's not because he's harder to write. No, the issue is that Superman is too often pulled in two different directions: one that wants to keep him as simplistic as he was pre-Byrne, and the other that wants to make him more complex by entirely deconstructing him. There's a third pressure from Hollywood that wants to keep Superman as a sort of modern-day, secular Jesus in New York.
Superman needs a better utilized supporting cast, a richer environment, and more complex villains who both directly challenge Superman's values (he needs a more specific purpose) and speak to the human condition. Get all of those elements, plus good action, without losing the essence and persona of Superman, and I think you'd have better quality and better received Superman films.
Edit: Just to give a few examples, some of which have been mentioned here, this is where utilizing the Daily Planet more (and Clark Kent) and allies could really help. Yes, Batman has gadgets and tactics. But as you note, he's also a detective, and has an important detective ally. Clark is an investigative reporter, not too dissimilar from a detective. Use that more integrally in a story, rather than having Clark serve as a commercial break or the Daily Planet as mere awestruck or imperiled observers. Superman has also had many allies; use them to make up for all those tactics Batman uses. And perhaps give Superman an organization and "idea" to challenge him, something that not only requires more people to beat, but also something that needs to be overcome by more than just brute force. Superman can be more than just his fists, it just requires someone willing to actually do something more with the character.
