So, it came to me the other day that there's a certain lack of creative ambition when it comes to mainstream film-making, it certainly seems like there are now more small-time films being made than ever on niche subjects but the big studios seem generally afraid to invest in new ideas. Hollywood is stuck in an endless cycle of either remaking the same films or remaking the same formulas with ever so slight changes - just enough new to interest people but not enough to make a really original contribution to film.
Oh, and Transformers movies.
In the case of Philip K. Dick, I think it's more that his stories are challenging in the way they depict the world overall, and more often than not he leaves a trail of bread crumbs from our world to theirs to show something deeper about our own self-destructive tendencies and potential failings; Ellison's work is darker and more individualistic, 'I have no Mouth' and some of his other stories would do more on film to challenge the happy ending cliché.
Admittedly a lot of these stories, and a lot of the stories that remain unmentioned (the vast majority), have elements that have been touched on in films before – we've seen post-apocalyptic worlds where man is no longer the dominant species, we've seen crazy master computer with incredible power, we've seen films where authoritatively controlled 'perfect' societies are everything (thanks Logan's Run!) but the general point is that there's always more that we could be discussing, there's always more ways that film can challenge what we think and what we know.
The best Sci-Fi comes from two things: the desire to wow and the desire to tackle challenging ideas, there's nothing wrong with explosions and action but if there's no depth, no purpose behind any of that then a film inevitably falls flat. At the moment it feels as though mainstream Sci-Fi is stuck in something of a rut, and until it get's that desire to break the mold and challenge the audience intellectually I don't think we're going to see many big budget Sci-Fi films that do anything other than wow on a superficial level.