X-Men is set in
earth 616, and like a fantasy (which no, does not take itself seriously). Fantasies like X-Men, Spider-Man and LOTR set their rules in the beginning and follow them through. Arguably LOTR is set in our world, more or less, since the environment and peoples are all humans in various forms. Same with X-Men.
X-Men doesn't "take itself seriously" when you have a world where people shoot lazers from their eyes and wear hairdo's like Logan's.
Munich is a movie that should be uptight about things like what is real.
We've seen what is happening with
Transformers which has already inspired fan backlash. That is a movie that takes itself seriously, even to the point of questioning whether the robots should speak.
Just because a movie deals with a serious topic (like LOTR) does not mean it takes itself seriously. If that were true it would have abandoned Middle Earth entirely. Do not confuse grit and story with "grounded and reality". Talking trees are grounded in what reality, should I go ask my forrest...maybe they can tell me

. The chances that they speak english, that they look human. If LOTR "took itself seriously" they would have abandoned these concepts in lue of something realistic. But they did not. They stayed true to the story, which was fantasical and at times unbelievable. Star Wars much the same.
Movies are good when they take risks. FOX did an X-Men franchise by the numbers. Don't make them out there, don't make them wear superhero like attire (not one here is even asking for yellow spandex), don't use characters besides Wolverine and Magneto (any one remotely familiar with the comics can tell you why that is a problem), don't use space, don't use unbelievable mutant powers...etc.
Superhero movies are only good when you don't take it seriously and have fun making them. When you throw caution to the wind, and attempt those major SFX battles and scenes you can only get in Superhero franchises. Batman, Question, Nightwing and DareDevil may be able to get away with smaller more realistic stories. But X-Men, Avengers, Fantastic Four, Spider-Man and Superman should never be brought down so as to restrict them. The comics ought to stand as a template, and X-Men is anything but realistic.
- I think in the end, it was the cast (and not necessarily their portrayals) that saved this movie. While the may have not stayed true to the characters (which mainly they didn't) they did do a good job. Ian Mckellen, despite wanted to turn humans into mutants (something Magneto would NEVER do...mutation is a gift and superiority to him) in X-Men 1, did a great job of capturing Magneto's attitude and manuerisms. Kind of like Joker in Batman 89, not a definitive version or even exactly like the comics...but we knew he could do the part. Same with Stewart, who really struck us as Professor X. Even Cyclops, Storm, Colossus and Wolverine looked enough like their characters to at least fool us into believing they were them for an hour and a half. But if it weren't for those actors and actresses I think people would have seen through the crappy interpretation.