There's just something about the character that rings true. He's a famous superhero, but he doesn't wear a costume or come from another planet. He's a mad scientist, but he doesn't cackle or plot or soliloquize. He's an odd guy with a diverse collection of obsessive hobbies and an even more diverse collection of friends, who are world-class experts in their fields while also being strange and geeky people. And somehow these people aren't his minions or his sidekicks: They're colleagues. He and his band work on things that nobody on Earth has ever heard of, but they don't seem too excited about that -- there are no breathless gasps. It's just part of their usual routine.
There's something about this guy, his lab, and his team that reminds me of the actual basement of the physics department at Cornell, and of the actual people who you might find wandering the hallways of such a place. A place where the pile of junk in the corner is actually the remains of a Nobel-winning experiment from 1967, and the guy who just asked you how to find the men's room is the Secretary of Energy.