The other day I got into an interesting conversation on twitter with fantasy author Sam Sykes. I was complaining about the Nebula shortlist leaving off a few books I thought should have been included, specifically Emily St. John Mandel's Station Eleven and Robert Jackson Bennett's City of Stairs. The latter book, I asserted, was the only fantasy novel I read in 2014 that moved the genre forward, and argued that this merited its inclusion. Sam took issue with phrase "moving the genre forward," and he has a point. I probably should have called City of Stairs "the most innovative, trope-busting fantasy novel I read in 2014."
Sam also questioned whether this was even a good frame of reference to use for awards, suggesting that a lot of books that get categorized as "standard" or "fun" actually have a lot of depth to them--depth that frequently gets ignored in critical discussions of the year's "best."
I agree. A great example of this would be John Scalzi's Old Man's War books, which can be read as straight adventure, but which--when you scratch the surface--are actually problematizing and subverting the Heinleinian source material. They are smart, clever and--crucially--fun. There are loads of other examples, one of which (Baptism of Fire) made my Hugo list.
That said, a book's impact on the field of science fiction or fantasy literature should, I think, be one of the foremost considerations when voting for awards. Actually I think it should be the second consideration, after an assessment of the book's overall quality. This is why I think it's so fundamentally disappointing that SFWA voters left Station Eleven and City of Stairs off the shortlist. These are incredibly good books--well-written, well-crafted, engaging and memorable. But they are also both breaking new ground and charting new paths for their respective styles, post-apocalyptic science fiction and epic fantasy. To me, at least, that's the essence of award-worthy.