If you're writing about one real person in history, you can soak up that person as a human, collect all the things you can gloss over in a documentary. But to balance five or six of them, there isn't time to do justice to each character. And if you get too heavy on the science, you'll lose the audience.
Einstein was a really interesting guy. He wasn't some dutiful little chap who went through the academic system and did everything proper. He had an enormous ego -- any lesser ego would have given up. He publishes this stuff and nobody pays attention for four years, but he is possessed -- and that's what makes him hell to be with as a human.