I think (even though it isn't well reviewed) Tales of Earthsea shows that they do sometimes make adaptations.

Not faithful adaptations, to my knowledge. They tell their own stories, and they do a good job of it, but they don't tell other people's.

The Earthsea adaptation was more of an action film than the books were action books, which happens to Tolkien adaptations too.

Funny you should mention Studio Ghibli right after I cited the animated version of The Hobbit. ;)