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.
O my! Why has not , almost all, great prose science fiction not be adapted? Great Westerns and Mystery's. I think great science fiction is still unjustly unknown. Recently a movie like Interstellar (not a bad movie) but Anderson's Tau Zero would have been more interesting (if done right). Why that goof ball I Robot , awful film, when Harlan's Ellison's elegant screenplay for I Robot is out there? What the heck does The Stars My Destination lay fallow? Gad! A space opera like no other. There is tons and tons of really great SF , some World Building never touched, Poul Anderson's Technic History , space opera 10 steps beyond Star Trek.
Well I don't consider Man in a High Castle second-tier, it is a great novel.