Here is a favorite quote of mine:
As Christopher Isherwood once said to Cyril Connolly, real talent manifests itself not in a writer's affectation but "in the exactness of his observation [and] the justice of his situations."
It's rare that I come across such a succinct expression of so much of what a writer is supposed to do with his work.
Writers are first and foremost observers, mainly of human behavior. Everything they invent or imagine is in some way related to what they have observed and in the manner they've observed it. Place someone of Tom Clancy's bent in 1950s Indochina, and he will see (and report back) entirely differently than, say, Graham Greene would or did. Each of those flavors of observation is going to draw a different audience: Clancy for those looking for a spy yarn, and Greene for those looking for ... well, a spy yarn, but one with some sinew in its soul as well as some meat on its bones.
Writers who look but do not see rely on the reader to finish their job for them. This is not the same as an author dropping hints; this is the author skipping school and hiring someone else to take his finals. When I read some fantasy author going on and on about the hem of someone's dress or the royal blue of the night sky, I feel as if I am in the hands of someone who has merely fallen back to the tropes of other fantasy writers, who is getting their inspiration from other books and not anything lived, seen or felt. When Joseph Mitchell gave us Joe Gould asking for hot water and adding ketchup to it to create a poor man's tomato soup, that was a simple but entirely correct piece of observation taken from the worlds both men inhabited. It told us something, showed us something, explained something.
The other half of the formula, the justice of an author's situations, is tougher to explain well but just as important. Every author sees the world differently and brings their own sensibilities to what they see. One could never mistake Herman Melville for Robert Musil, and not simply because they lived and worked in different centuries. Their senses of what had to happen in a story and why would have been entirely dissimilar even if they have been contemporaries. Under the hand of one writer, things would happen to a character that would never happen on another writer's watch — and for reasons that would also never occur to another writer. It's hard to see Philip K. Dick creating a character like Jubal Harshaw, just as Heinlein would most likely not have created someone like Rick Deckard — and if they had, they would have been spun out along very different lines.
This is what is meant by an author's style — not their choices of words, not their sentence constructions, but what they see in the world and how they report back on it. We take that much more pride in a writer who sees the whole of something instead of just the parts that appeal to his prejudices (or the audience's). We feel a greater sense of the epic in Tolstoy than we do in P.G. Wodehouse, not because Wodehouse is in the inferior writer but because the two men were seeing things on a different scale. But neither of those writers give me the impression they are more interested in an idea (theirs), a reputation (theirs), or a style (again, theirs) than they are the communication of a human connection. An author who is bound up with such things — with "affectation" — will miss the point of the very things he brings up. No, not even Tolstoy gives me that impression — at least, not the Tolstoy of Anna Karenina or War and Peace (save maybe for that last chapter), and certainly not Wodehouse in any of his incarnations.
I would be foolish to insist that SF&F authors only have one set of worldviews; from all I've seen they have a panopoly of outlooks. I mentioned Dick and Heinlein above, and there are plenty of others I could throw in who are at least as divergent as they: Bradbury, Lem, Delaney, Sturgeon, Moorcock, William Gibson, Terry Goodkind, etc. Some of them are polemical; some lyrical; some just interested in a ripping good yarn. What they fall into, more often than not, is the way their observations and justice are on the side of SF&F rather than anything else. Most of the time this is relatively innocuous — James P. Hogan, for instance, has fiction that's as mechanistic (if enjoyable) as any episode of Star Trek: The Next Generation. But SF&F more often breeds Hogans than it breeds a Lem or a Bradbury, in the same way romance fiction almost rarely gives us a Gone with the Wind. It gives us ideas, invention, panoramas. What it does not give us nearly enough is the fulfillment of E.M. Forster's exhortation to "Only connect!"
It might be argued it's not SF&F's job to be so literary. Meaning what, though? The more I read (and the more I write), the more I feel being literary is not a matter of language, but of what is seen and how. We do not think of Studio Ghibli's films as being beautiful simply because of the scenery, but for the way people we come to care deeply about inhabit those films. An author who only thinks of characters as chesspieces and deeper human truths as "issues", as much SF&F tend to do, will fail at generating such empathy. He may entertain, but he will not connect.
SF is no more disqualified from connecting than any other variety of writing. If anything, it is manifestly more qualified to do so — it's just that the majority of the time (as with most other fiction) that aspiration is shirked (not always knowingly) for the sake of things that seem easier or more immediately important than to only connect. But nothing else is, and I am not sure anything else ever will be.