If it's true that transgender people didn't think about this until the directors came out, the metaphor can't have been a very good one. That's likely more the fault of the studio than the directors.

A point of comparison is Harry Potter. Rowling is still coy about it—as you would be, given the money at stake. But every gay or lesbian reader, and lots of straight ones beside, immediately see what inspired lycanthropy. Not to mention the adolescent protagonist who moves out of his suburban closet to discover a hidden world at the back of a strange pub, where power comes from the point of a spark-shooting wand, and his latent talent for riding broomsticks makes him the most popular boy in his boarding school.

With Rowling's sense for wordplay, she must have been aware of that interpretation, even if it wasn't entirely deliberate. But it isn't just words: the whole structure of magical Britain, and the muggle world's surprising failure to notice things that are sitting in plain sight, are strikingly familiar to gay and lesbian readers who were around when the books were written.