One of the things that puzzles me about Hollywood is how they can remake stuff over and over when there are so many sic-fi stories that have yet to be done.
I doubt its a problem with rights- most authors profit handsomely from book sales from a movie release - even if they get paid squat on the movie itself. No, I fear this has more to do with the Hollywood agenda. The Left is anti-human and anti technology, so they will gravitate to stores like Dicks where the humans live in some nightmarish, morally ambiguous world, where the technology has usually play a role of catalyst. Don't get me wrong, I have liked nearly everything that Phillip K Dick ever wrote, but they are NOT tales of good and evil, or of bright futures for mankind. Hollywood shows you some sort of really awful totalitarian society in order to make the slightly less totalitarian society they envision seem benign in comparison. Orwell and Huxley have been treated to movie adaptations for the same reason.
Heinlein? That guy is a pro freedom libertarian. Can you imagine them making "The Moon is a Harsh Mistress" when the main moral theme is TANSTAAFL
Is really a miracle they decided to make Lord of the Rings, and did it so well, with its overt Christian Themes and clear cut Good and Evil story. Narnia, which was MUCH, MUCH easier to adapt, got funded only because of LOTR's success, and I suspect they screwed it up on purpose. In my mind the
horribly animated version is better ( I snapped it up for $10 when it was released, and even my kids prefer this to the CGI version - crappy animation and all - because its told properly. ) Simpy look at Aslan's stature in the film. He is not a giant, towering over all, but a normal size, regular lion. That fact alone was enough to make me hate it, as the producers obviously must have hated it.
Asimov? Really I think he is too intellectual in his tales for what Hollywood considers their audience. Not enough explosions and fighting you see, too much thinking and figuring things out.
Orson Scott Card is getting his shot this year with Enders Game. But Card falls in that same category as Dick- not as dark, but he tends to focus on tough moral questions brought on by technology.
A lot of Sci-Fi is about human exploration, living on interdependently frontier worlds, dealing with new and strange challenges though intellect, creativity and force , and all without the help of some nanny government. Hence those tales of an untamed frontier are ignored. For Hollywood its just not about the money. Its about the message. Its "art" you know. So they will make some agit-prop film about fracking that no one will see before funding a great story with a large built in audience - because that story has a message they find uninspiring or inappropriate.