Probably because of the obvious psychological complexity of its main character.
Batman, AKA Bruce Wayne, lives through the trauma of watching his parents murdered in front of his eyes as a young boy. In order to find some kind of retribution, he becomes a superhero who tries to save his city, Gotham, from crime.
And not just that – he also picks a disguise that is reminiscent of what was once his greatest fear: the fear of bats.
As a kid he found himself trapped in a well, surrounded by fluttering bloodsuckers who seem to want to attack him. But as a young man, he wasn’t going to continue giving in to that fear. He wanted to overcome it.
So (after a long and hard training period somewhere in a faraway Asian country) he exposed himself voluntarily to a swarm of screeching bats, standing still in the midst of the tornado, until he had overcome his fear. And thus, the legend was born.
But Bruce Wayne doesn’t just attempt to move past what used to haunt him by looking straight at it. He transcends it into his greatest strength, and embodies what once was the source of a severe phobia.
All his life, Batman is drawn to father figures, as Jared DeFife, a clinical psychologist and research scientist at Emory University points out. There is his one and only friend Alfred. There is the police commissioner, Jim Gordon. Even his great nemesis Ra’s al Ghul is initially a mentor and protector.
He wants to make up for the loss of his father, who left him a fortune to help Gotham’s neediest citizens. And he wants to show them his might.
All his life he felt obligated to avenge his parents’ murder by relentlessly pursuing the corrupt. But he also feels the need to live up to his father’s expectations, which have become his own expectations of himself.
Batman is an introvert, a man of few words. He doesn’t chat much with his respective love interests – or anybody else for that matter. He doesn’t talk. He acts. Which puts him — just like in the real world — in a difficult place when it comes to the opposite sex.
Every woman loves a hero. But he also has to be in touch with his feelings. And Bruce Wayne is not exactly a touchy-feely kind of guy.
Having lost his mother at a young age, he is unable to allow a woman to come close to him. The fear of opening himself up to further loss is just too great.
So he remains a lonely hero, a man who solely focuses on his mission. Even the last scene in the most recent movie (when he is seen with what seems to be Batwoman in a semi-romantic setting) can’t quite do away with that image.
And yet there is a tenderness and vulnerability in the man who had to put on an impenetrable armor in order to protect himself.
The most moving moment comes when we see the hero fall down, and in danger of succumbing to despair. That is when he hears the voice of his father saying to his young son: “Why do we fall? So we can learn to pick ourselves back up.”