Zach WeinersmithOffhand thought - I wonder if part of why sci fi and fantasy are so huge now is that a lot of the genres that would've scratched the same escapist itch are now hard to do inoffensively. Like a lot of 19th century adventure literature is oriented around white adventurers visiting strange cultures, romancing hot locals, stealing stuff, and getting away. Setting it among aliens or elves or whatever allows the same story, theoretically minus the dehumanizing.
Marc Etienne@ZachWeinersmith I think a bigger part is that authors who want to write historical fiction now need to know their history. Same with adventure locales: it isn't as easy any more to make up cultures in some remote areas of the planet any more, and if you do write about, say, the Congo you can't just make stuff up any more now that everyone has access to Wikipedia.
F&SF is free of those annoying pedants.