You don't know that. Things effect people differently.
I have no problem what The Dark Knight handled. Being that the films were given a more plausible approach or more grounded and believable, the themes can easily parallel what we are witnessing in real life. The Dark Knight was about a large scale response to a terrorist. Something that could easily parallel 9/11 or terrorism. But I don't think Nolan and co. sat down and said, "let's make a political allegory."
Why can't comic book films take on more serious subject matter? I think if they can touch into real world issues more and use it in their own films and how they handle that subject matter in context with the comic book element itself, why not? I think it makes the characters and story more endearing. And not just something we can look out of for escape. It can be escape, but it can also be confrontation. We can participate and discuss. X-Men uses prejudice and equality and the fight for the right of everyone. As in the comics. It is also something we are dealing with in real life. It's not the question of comparing these similarities, it's about people relating to them and understanding. It makes the story more involving and the audience would understand it more. And not just some mindless action film that comic books and its films have come under criticism for. Of course, have the comic book stuff we all love, but as clever filmmakers have done, tell a story that is mature. There's a level for kids to love and also for older audiences can look as well. It doesn't always have to be mindless fun. It can be, but not for everything. It depends on the nature of the characters. It fits the nature of Batman and X-Men, so use that. Spider-Man is fun and more light, but that doesn't mean they can't tackle more mature issues. Yet still falls in line with the spirit of what the comics were. SM2 did this. It was a serious film but had the comic book elements of fun and action. But it also told a great story that people could grasp onto.