yeah i think it (the neo-medieval fantasy genre as per Game of Thrones and also modernised-Medieval tripe-with-tits like Camelot, forthcoming) has something to do with how this kind of omnifantasy genre (Potter is part of it too) has displaced "proper" science fiction, by supplying some of the needs (for otherness, adventure, escape) that s.f. supplied but without the critical edge
my idea of Proper S.F. comes from being a lapsed and then partially reactivated fan whose fandom was determined almost entirely by the New Wave of s.f. (and then later a bit of cyberpunk)... i loathe fantasy and space opera... my idea of what s.f. should be is speculative fiction, scenarios based on a projection from current trends and knowledge (or alternative history, which is the same kind of methodology applied to the past -- or to put that another way, s.f. in its proper speculative form is a form of future history, the historical method projected forward)...
oh i enjoyed Tolkien as a wee lad (read Lord of the Rings age seven, and several more times before the age of 12) but generally speaking have minimal tolerance for the epic, the heroic romance, etc.... i find Peter Jackson's LOTR trilogy pretty unwatchable, all those shining eyes-y fare-thee-wells and arms-clasped partings of the way... this kind of literature/TV/films is for wee lads and wee lasses... as Alan Kirby puts it, it's "children's entertainment", a world without the two key aspects of adulthood: work and sex. Which means that it is a world without class or psychology; Marx or Freud. A reversion to the clear-cut universe of allegory, sans duality, contradictions or internal conflict. It's also a world completely without humour.
The unstoppable rise of fantasy (including a whole genre of masquerading-as-s.f TV -- Lost/Battlestar Galactica/Caprica) really seems to relate to a general culture-wide inability to envision the future... instead we get the Middle Ages projected onto the future, or into outer space, or into a sort of postmodernly scrambled pick'n'mix pseudo-past, e.g. from Joy's piece: "Although Martin has done much historical research, “Thrones” is not shackled to any specific reality. According to [TV writer] Benioff, “It’s built on a vaguely Western medieval skeleton, but he’s pulling from the Mongols, native Americans, India, all these elements get woven together into this new tapestry..."