That's true. Ghibli isn't Disney, though. It's Hayao Miyazaki's creation. A lot of his work does get picked up by Disney, but I don't think there's an agreement.
The story of "Howl's Moving Castle" was a lot different from Diana Wynn Jones's, particularly Howl's characterization and just about everything in the second half, so I agree with you there. But I would totally love to see something done with the same attention to ambiance, color, and movement that Studio Ghibli's work has. I could do with a different (sharper) animation style for the people, though. I'm not sure the faces are quite right for the feel of Leviathan, now that I'm thinking about it.
Hmmm.