Joseph Campbell killed genre fiction. Mostly SF, but genre fiction in general. It wasn't his fault. Joseph Campbell did something fairly brilliant: he saw a way to take traditional stories and build them together into a single taxonomy. He found elements that crossed cultures (although it's definitely got a Western bias) and synthesized a sort of "grand unified theory" of mythology and literature.
I'm not here to debate the veracity of this idea. Campbell is right in enough ways that his ideas have explanatory power, even if there are cases that fall outside of his scope.
Sometime between when he had those ideas and today, people blew his findings out of proportion. Repeatedly, I've dealt with people that use Campbell to defend unoriginal literature, claiming he proved that all stories were the same anyway. Those not as well read might not name-drop Campbell, but they like to trot out the "finite number of stories" canard.
It's simply not true. While there are some commonly used story templates, there are as many unique stories as there are ways to arrange words into meaningful sentences.
And this gets us back to the death of genre fiction. Modern science fiction, especially in TV and movies, takes the stance that stories are the same, and are inherently about the characters, and that science fiction or fantasy is just another costume to dress the same story up in. Some might consider this the "literary" tradition. In this approach, all the trappings of the setting exist only to drive up the special effect's budget and provide trailer-fodder, while the story could be told equally well in any other setting. Star Wars is the most obvious example of this: sword and sorcery fare in spaceships. But pretty much every Star Trek episode from some point in the middle of the TNG era also fits the bill.
What you find is that the setting is just props and costumes. For some stories, that's fine, but genre fiction used to be about exploring ideas. Whether it's taking a modern idea and casting it in a different light by analogy or imagining a world drastically altered by some new technology or idea, in classical genre fiction, it was always the ideas that took center stage.
In some cases, notably the likes of Heinlein and Asimov, the result was cardboard characters that generally could be grouped into a handful of niches, few of which ever truly leapt off the page. At the same time, these books are rife with ideas. Different social codes, technologies that reshape society in strange ways.
I'm not trying to say that character driven drama is bad and idea driven drama is good. But the best genre fiction can do both. Sterling's Holy Fire builds a fascinating world, and then shows it to us through the eyes of a newly rejuvenated octogenarian learning about the gerontocracy from the ground up. Vonnegut, of course, was a master of mixing bizarre ideas with likable characters.
My main complaint is that the pendulum has swung away from "big ideas", at least in mainstream sci-fi. It's hardly dead, but sometimes, it feels like somebody slit genre fiction's throat.