Ursula Le Guin of Earthsea fame put it nicely:
Commodified fantasy takes no risks: it invents nothing, but imitates and trivializes. It proceeds by depriving the old stories of their intellectual and ethical complexity, turning their truth-telling to sentimental platitude. heroes brandish their swords, lasers, wands, as mechanically as combine harvesters, reaping profits. Profoundly disturbing moral choices are sanitized, made cute, made safe. The passionately conceived ideas of the great story-tellers are copied, stereotyped, reduced to toys, molded in bright-colored plastic, advertised, sold, broken, junked, replaceable, interchangeable.
What the commodifiers of fantasy count on and exploit is the insuperable imagination of the reader, child or adult, which gives even these dead things life- of a sort, for a while.