I wouldn't say he learned nothing. They made a specific point of the fact that Doomsday hit him once knocking him into a building that was deserted because it was late at night. Then Superman immediately lifts him into orbit to avoid casualties. These things are even stated by a newscaster. In fact, Superman starts punching him with the intention of getting him so far out that Doomsday breaks free of the Earth's gravitational pull. But the military messes it up by launching a nuclear missile. Doomsday falls back to Earth. Even then, they emphasize that he landed on an abandoned island. It's Batman that leads Doomsday into a population center and Wonder Woman wants to know why he did something that stupid but Batman explains it's because there's something there that can defeat him.
On the one hand, this shows an awareness of some of the things people didn't like in MoS. So, rather than realism, it's empty buildings and deserted islands and Superman considering casualties. Yes he's still mopey but, then again, I would be too if that stuff was happening to me.
In a way, he does triumph over it in MoS but I know what you mean that, in other ways, he doesn't. He keeps saving people but he spends years traveling and hiding rather than deciding to become a symbol. Let's say it was five years. There's really no difference between 2008 and 2013 as far as the world being ready.Well the Wonder Woman movie was pretty successful and that movie was ultimately hopeful and optimistic despite being set in WWI.
Here's what I would suggest, you can make the world around Superman darker, but Superman himself should always remain the same, make post 9/11 paranoia something he triumphs over, rather then something that defeats him, over and over again.
In a way, that was StM (except for Krypton and Smallville). When you look at Perry White, Jimmy Olsen, Lex Luthor, Otis, Eve Teschmacher and the general feel of the movie including Clark Kent, Superman is almost the only character that is played straight and even then only as Superman, not Clark. But that's a very dangerous undertaking. As you said, what's funny and what's stupid funny is an inch apart and casting the wrong actor could have destroyed the whole movie.That's what they did Wonder Woman and Captain America, optimistic characters in darker settings who refuse to give in and fight for what they believe, their beliefs are challenged, but not defeated.
Though there is also the Thor Ragnarok route, where certain elements stay serious (nothing really funny about Hela), but a lot more comedy and wackiness is introduced. At this point I think you could get away with having Mr. Mxy be a annoying secondary villain who ultimately becomes a comedic foil for Superman. With that route it really depends on the execution, comedy is certainly subjective, but Superman would be the ultimate straight man.
I hadn't quite thought of it that way but that is true. Every big screen version of Lex Luthor has been a campy comedy character in some way. Kevin Spacey was probably the best of them. He conveyed both the humor but unleashed the real monster behind it. Gene Hackman, though a great actor, only showed the comedy. The monster was there by default but he wasn't playing it. And Jesse Eisenberg, I just kept totally forgetting he was supposed to be Lex Luthor because he was playing the Joker better than Jared Leto was. In fact, based on performances, Eisenberg and Leto should have switched characters.I would say the setting should be modern (the fact there was no minority characters in Superman Returns is jarring, IMO) but maybe have retro elements in there as well.
Though I will say I want a better version of Lex on screen, because I am sick of the campy idiot we constantly see in the movies pretending to be Lex. I would make Lex far more serious, make him far more competent