The Force knocked away the flying bone
I blame Star Wars at least in part for derailing the promise that was 2001: A Space Odyssey.
Enterprise was just not that good; the characters were not interesting. The producers could have done so much with the early days of the series history, but they wasted the potential.
I think SF is just in a lull. Soon enough it will go in a new direction. Plus we now have common devices that even ten years ago would have been considered science fiction.