The main trouble is his adversaries, because he is so powerful, from another planet, only one of his kind do dah, well it cuts down the challenges he has to face. In every outing there has been they have had to resort to him getting cats out of trees, battling natural disasters, either natural or created/caused by the bad guy and the fucking weather, all extremely dull really. There is fuck all they can do about it as well, as its set in stone he is near invincible.
In the Singer version they have him stop a bank robbery, the robbers have a helicopter and a fucking Vulcan cannon off an F-15 on the roof, just so he can stand in front of it and show how tough he is, oh please do fuck off.
One way to go is inward, less action man, more introspection. The I'm so powerful, this is all such a burden, I cant be everywhere and save everyone, I'm an intergalactic superhuman invincible emo teenager with angst and no one understands me version. Oh not to mention the I'm just a teenager in love with Lois Lane and I wanna fuck her, but cant because I'll blow out her spine when I shoot my beans version. Sounds dead fucking interesting and I don't think.
The first two Reeve versions there was at least a progression of story, the first was an origin setting up the second, the second gave him some meat to deal with in General Zod and co. That was what the original was for, second was generally botched because of the change of directors and tone. A time honoured tradition of people who don't understand comics, yet try to make films out of them. They think when making comic book films that the comic bit means comedic and they aim squarely at the kid market, to sell toys whoopee! Thankfully this aspect seems to be happening less and less. However, don't think they aren't waiting there to do it again and fuck it all up, only have to look at how the '89 Batman run went.
You also have the fact that politically he is very iffy these days. It can work in comics, due to the hyper reality on the page. However on film, where these films need to be generally set in the real world, truth, justice and the American way is so out dated. He might as well stand for neo-con fascism and multi-national corporate greed.
I mean that also ties into the villain aspect. One which was so ruthlessly parodied by Myers Doctor Evil. Lex Luthor is a fucking school boy really, he could rip off all kinds of money and be king dick and never even break the law these days. Shall I steal nukes and try to cause an earth quake that makes California fall into the sea or leverage buy out a car company and liquidate it? Hmm tough choice. Ooh what about starting a war and plundering a countries oil reserves? Now there is the American way in action.
The point is we live in a world now where the lines between good guy and bad guy are really fuzzy, its not so clear cut as east v west communism and free market capitalism cold war. Cant even go the route that Hollywood was going after the fall of the Berlin wall, of having religious extremists be the big bad guys, to iffy, to close to reality, not in a film which is meant to be family friendly and appeal to the widest demographic possible. The first Ironman does skirt this reality, but then that's part of Starks character arch, from arms dealer to super hero, so it works.
If they are going to do Luthor they need to make his motivations beyond money, they have to make him a nutter, who just wants to wreck the world, oh wait, oooh I know, like a mad man who just wants to watch the world burn, I've heard that before some place. You see Batman will be better, with his moral ambiguity meeting Superman's rigid law abiding citizen.
As I said, super boy scout is really difficult to bring to the screen, it just boils down to him being a cardboard cut out dickhead of a character, who no longer works in todays world. He doesn't have a darkside, he is boring as fuck, he is actually more Clarke Kent than he is Superman. Helps old ladies across the street, got his campfire singing Kum ba yah badge an shit. Ok lets make him dark, lets have him shag birds, get drunk and flick peanuts breaking mirrors in bars, that worked.
A way of doing it is to maybe set it in the past or make the reality you put him be ultra fantastical, a world in which he fits, no Nixon, no Vietnam, no cold war, no 9/11, 1950's values, which the original Donner films did really, so he doesn't jar the senses with his bullshit. Lets be honest, that sounds like it would be fucking shite and its been done.
See when you add up all those factors, putting Batman in a film with him is a great idea. Not just from the cross over omg fanboy we'll see's dem on screen together squeeeee shite! No, but as I have said previously, to give Superman something to bounce off and reflect. Its common enough to have a hero in a film be a cardboard cutout Dudley doright dildo, but have the adversary be all smart, dark and edgy, that's Batman to a T! Oh usually English, but not this time. So it might just turn out to be the best thing they ever do for Superman, making him less of a dim-witted apple polishing schoolboy, but a 3-D interesting character with a bit of depth.
Man of Steel is basically the first two Reeve films in one go, does away with the Luthor element, goes origin and straight for Zod, it kinda works, because its basically the two films mashed together. They have kinda shot their bolt with having Zod appear as the adversary in the first film, it really left them nowhere to go in villain terms. Does make you wonder if this whole Batman combo thing isn't as rushed as it seems. Maybe it was always planned they would do a combo movie as a sequel, as a two fold way of turning Batman over for a quick reboot and raking it in with a cross over.
They could of done Luthor next, the whole brains brawn thing that goes on between them, but then this version of Superman isn't exactly a dunce. So having Batman put him in his place makes sense and will be rather fun really, as long as he beats the fuck out of him.
It will be interesting to see how they approach it really. If they follow the Dark knight arch, that he has become a stooge for the government, fights wars for the US and such it might work. That politically he follows the government of the days political line and the rigidity of the law. But given what happened in Man of Steel, it doesn't seem like they will be having him go the way of g-man. Although that can be changed, so that might be the arch, that serves to bring him into conflict with Batman. Don't know how easy that will be to get on screen, as all that stuff happens years later and they would really need to do a film in the middle to get there in the third.
Ah, now maybe that's the idea. This first one ends with Superman having to make the deal of becoming the G-man stooge, as long as everyone else goes away and behaves. Setting up a third film, where Batman comes back and they are in conflict, then Batman beats fuck out him. That scenario would also tie in with doing a JLA film, maybe in the middle. Showing all these characters, that the government then wants reigned in, and they use Kent as the means to do so.
It might work "You sold us out, Clark. You gave them the power that should have been ours. Just like your parents taught you. My parents taught me a different lesson... lying on this street... shaking in deep shock... dying for no reason at all. They showed me that the world only makes sense when you force it to."