Pothealer said:
Is it my imagination, or, once you are recognized as an author of "novels," it's hard to break into sci-fi, and vice-versa? It seems that there are some really fantastic wordsmiths in sci-fi and fantasy, but popular mindset always relegates them to that one world. If they try to write a piece of conventional fiction, it isn't well-received. Stephen King is the only guy I can think of to whom that rule doesn't seem to apply.
No, it's just a matter of genre and non-genre publishing and who markets to whom. Plus, maybe a little resistance to authors breaking away from their "brand" of one type of fiction to another. The wordsmiths who not only write sf/f but are published by sf genre publishers and marketed principally to sf fans, though some marketing to more mainstream audiences is sometimes done. Therefore, they are seen mainly as genre writers. This is different from non-genre sf writers who sometimes do sf novels, published by non-genre publishers and marketed chiefly to the mainstream, such as Michael Crichton and others.
Another factor is that most sf/f authors published in the genre like to continue writing books of this type. But for those who want to write other types of fiction, markets do exist. Isaac Asimov, for instance, published mysteries. Jonathan Lethem, who did several sf novels in the genre, then went on to write a very successful mystery novel, "Motherless Brooklyn," and a non-genre fantasy novel, "Fortress of Solitude." A number of sf/f writers have also written children's fiction, westerns, horror, and so on.
Horror is a market that straddles various fields. Horror novels can be sf, fantasy or simple suspense. It has a fan audience and is identifiable as a category, but such an audience has never been large and organized enough for horror to move out of being a sub-genre of mainstream fiction and an adjunct to the sf/f genres. King's first publications were in horror and most of his work has been in horror to great success, and thus mainstream fiction. He has also, though, in the course of his long career, written dark fantasy published by genre publishers and non-genre fantasy that is not really horrific. As part of the horror genre, he may seem to move freely among genres, but that's partly because he is chiefly marketed to mainstream audiences, not just genre audiences.
As more and more non-genre writers use sf and fantasy elements in their work, and as more cross-marketing between mainstream and genre audiences is pursued by publishers and booksellers, the difference is likely to become less and less important, and genre writers putting out other types of fiction are likely to find less resistence from mainstream audiences. But, it's only really going to work if the genre fans let their authors sail off into other waters and not cry abandonment when they do.