Great responses so far.
I was reminded today of something I read about Ian Fleming's James Bond novels, which were really all wish-fulfillment. Not only for the author, but the readers, who in 1950s austerity Britain loved to imagine themselves drinking Dom Perignon 48 (or whatever), getting their shirts handmade in Jermyn Street, smoking expensive cigars and wasting shady foreign types who threatened Britain's interests. By drawing on his own wishes, and having them equal a large proportion of the reading public's, Fleming had a massive success.
So far, so obvious. Same goes for the "sex and shopping" novels. And same for Harry Potter, I imagine -- replacing the reader's own school with something rooted in much the same culture but magical and adventurous.
But is it harder to do in most SFF? Though a reader might get a vicarious thrill from reading about a sword-wielding hero, hacking orcs to bits isn't something most people really want to do, or can translate to their real-world selves.