The careful readers among you will notice a missing word in the second half: acknowledged. And that, for me, is the key issue.
I joke, quite often, that the category of Magical Realism was invented so that no one had to admit that a speculative fiction writer had won the Nobel Prize. And it's not just Marquez - try Lessing, or Saramago, or Heaney. But if you look on the bookshelves, these authors, like those on the Booker list, are shelved with Literature, not fantasy.
In Young Adult literature, the genre categories don't seem to matter. What is arguably the biggest prize in YA lit went to a work of speculative fiction this year: Neil Gaiman's The Graveyard Book. As far as I can tell the award goes fairly regularly to speculative fiction, and no one seems to make a fuss.
I'm not sure what causes this difference. Perhaps because in "kids' books" we expect fantastical elements? Well, maybe, but then I'm not sure what people are reading that makes them not expect fantastical elements in works of literature for adults. Stories that are generally considered to be great works of Literature - the Odyssey, the Aeneid, Beowulf, Hamlet, Paradise Lost, the Divine Comedy, The Tale of Genji - all of these have speculative elements. The presence of ghosts and gods doesn't make any of these stories less great.
I describe what I write as speculative fiction. Not because I am arrogant enough to think that I'm getting on the longlist for some fabulous Literary prize someday, and I need to categorize myself as something other than a writer of Fantasy, but because I truly believe that the truest genre division is between mimetic fiction, and speculative fiction. And really, I'm promiscuous in my literary tastes. I don't care on which shelf I find my favorite book. But I do wish that people would realize that the category on the shelf is not an arbiter of the quality of the writing that is shelved there.