This snippet of an interview of Gene Wolfe by Larry McCaffery was interesting enough for me to go read the whole thing. I whole-heartedly support what Wolfe says in this paragraph:
Gene Wolfe: It's not so much a matter of "advantages" as SF appealing to my natural cast of mind, to my literary imagination. The only way I know to write is to write the kind of thing I would like to read myself, and when I do that it usually winds up being classified as SF or "science fantasy," which is what I call most of my work. Incidentally, I'd argue that SF represents literature's real mainstream. What we now normally consider the mainstream—so called realistic fiction—is a small literary genre, fairly recent in origin, which is likely to be relatively short lived. When I look back at the foundations of literature, I see literary figures who, if they were alive today, would probably be members of the Science Fiction Writers of America. Homer? He would certain belong to the SFWA. So would Dante, Milton, and Shakespeare. That tradition is literature's mainstream, and it has been what has grown out of that tradition which has been labeled SF or whatever label you want to use.
I was trying to get at this in A Theology of Fiction. It is an idea that has been growing slowly for me, with my first expressions of it in my review of The Song of Roland. Now I’m wholly on board with the idea that realistic literary fiction is a historical aberration.