It's been pointed out, frequently, that Tolkien sold the movie rights
himself, and so (it's implied) we can't dispute his willingness to have one
Here's a little more about that:
"Brass bands playing, big drums thumping, the publicity circus for the
mythology-movie _The Lord of the Rings_ draws near; but all I can hear is
the chuckle of John Ronald Reuel Tolkien, 30 years ago, telling me that he
had consented to a film rights deal with one of the big studios.
"'Not that there's any chance of a film being made,' he said. But the deal
meant, at least, that film company lawyers would save him from the
distraction of guarding his copyrights from people making Hobbit t-shirts
or plastic Gandalf toys, and let him get on with his work."
- Bill Cater, Daily Telegraph, Nov. 29, 2001