Brian Stableford, in his indispensable The A to Z of Fantasy Literature (Scarecrow Press, 2009), asserts:
"Literary experimentation in fantasy is to some extent parasitic--and not only in commercial terms---at the expense of the wide and consistent appeal of fantasy's commodifiable formulas" (page 84, in the entry on "Commodified Fantasy").
What a great springboard his statement would make for a panel discussion at, say, Readercon or Arisia, or at the Brooklyn Book Festival! Stableford is an astute, measured commentator on the fantastical genres, with an encyclopedic knowledge of the field-- his views merit serious consideration.
What precisely does he mean by "parasitic"? What qualifies as "literary experimentation," what answers best to "fantasy's commodifiable formulas"? A long-running debate, both within the genre and much further afield (echoes of Aristotle, Horace, and Cicero carry down through the clashes); Stableford's comment above is a part-response to Ursula K. Le Guin, whom Stableford cites in the entry as the source of the term "Commodified Fantasy."
Alas for the lack of time to explore the worthy debate further right now-- but I think the lobster and the canary shall return (here or elsewhere) to the evergreen contest between "commodity" and "experiment." Besides Le Guin's observations over the years, Gary K. Wolfe's Evaporating Genres: Essays on Fantastic Literature (Wesleyan University Press, 2011; Amelia Beamer co-authored some of the essays) figures here, likewise Farah Mendlesohn's Rhetorics of Fantasy (Wesleyan University Press, 2008), and the extensive work by respectively David Hartwell and John Clute. It will be interesting to map our genre-focused explorations against more general recent discussions about fiction and its uses. Zadie Smith's "Two Directions for the Novel" (in her collection of essays, Changing My Mind, published by Penguin, 2009) comes quickly to hand, as does Orhan Pamuk's The Naive and Sentimental Novelist (Harvard University Press, 2010) and the insights of respectively A.S. Byatt, James Wood and Marjorie Garber. And not to forget classics such as E.M. Forster's Aspects of the Novel, Wallace Stevens's The Necessary Angel, and the critical work of Virginia Woolf, V.S. Pritchett, William Empson, and Owen Barfield.