Um. How about this for a reason: your writing, especially more obscure/OOC centered stuff, transcends expectations of fanfiction. Most people don't presume to review original books, don't write to the authors or even comment on their bogs. I can't imagine anybody reviewing in the same sense "Children of Hurin", even with more or less available more or less author - for example. People seemingly review fanfiction mostly to express some sort of camaraderie (with ficwriter) in shared experience (of the original).