Something that I've wondered about pretty much since I discovered him, is why Jack Vance has never, as far as I'm aware, been adapted for movies or television. Not that I mind the lack for my own sake—his work is perfect as it is—but Phillip K. Dick was a second-tier writer until studios began adapting his stories, whereon he became a household name even among non-SF readers. I'd love to see that for Jack Vance, and a lot of Vance's stuff seems much more amenable to adaptation that Dick's.
A lot of his short stories are based around a single clever idea and not amenable to adaptation, and his later work but pretty much any of his novels or novellas seems like it would make a compelling movie of the sort studios like to make. Jack Vance's longer works already tend to contain fast-paced action and the potential for dramatic special effects. I could the award-winning "The Dragon Masters" making a great movie for someone who has a budget, but I could also see The Five Gold Bands/The Rapparee made on a relative shoestring (thanks to justified rubber forehead aliens) and still working well. Even many of of his more obscure novellas like "Crusade to Maxus" and "To Love Forever/Clarges" seem like they'd make compelling films.
Some of his series works, such as The Dying Earth, The Demon Princes, and Lyonesse are too convoluted for a film, but seem like they'd do well as television series. Particularly considering the success of Game of Thrones, and the fact that George R. R. Martin himself described Vance as the greatest living SF writer (back, obviously, when Vance was still alive).
So does anyone have any idea why Jack Vance's work has never been adapted? Has he just not been discovered? Did he refuse to sell screen rights? Or is there something I'm missing that would make his work unsuitable for the screen?