Mr. Banks

We saw Saving Mr. Banks.
It was a good movie. And a fun perspective too.
I can completely understand how the author of Mary Poppins must have felt. It must be so hard to give up your characters and story for someone else to interpret in their own way. And their interpretation may go against your views. It seems like it would be such a gamble. Movies based off of books can be so amazing. Or they can also turn a good book into a complete piece of garbage as a film.
I can see her reluctance with Disney.
As I've said before, I generally love Disney. But they do twist a lot of stuff around to fit their ideas and their model of a story. For example, Frozen has almost no similarities to the original fairy tale, besides an ice queen and a frozen heart.
Up to the point Mary Poppins was made, I liked most of those Disney cartoons (and a lot of the film movies were good too, though I haven't seen all of them). But nowadays Disney makes so much stuff that a lot of it just isn't good. And a lot of it I'd never even heard of, though it still looks kinda weird.
It makes me wonder though. Under what circumstances would I turn my characters and stories over to another?