Burton’s a great and unquestionably imaginative director, but he didn’t imagine this movie. As I understand it, Disney hired him to direct only after Ehren Kruger wrote the script. The script was, of course, based on the animated Dumbo, which itself was based on an unpublished storybook (more like a storybook proposal, really) by Helen Aberson and Harold Pearl, with art by Helen Durney.
I’m sure that Burton is doing a great job on Dumbo. But it didn’t come from his imagination.