Literary awards confer expectations, not just of quality but of content. If you think an award is for the best apple in the barrel, you're going to be surprised when the judges pick an orange. Even if it's a good orange.
I think this goes someway to explaining the mixed reception Redshirts has had as last year's Hugo winner. It's a slim, gently comic work with a big heart in a genre which has traditionally tended to prize density of thought, volume of book and overt seriousness of purpose.
Outwardly, Redshirts is a Star Trek parody, which may also have triggered a certain snob response among fandom. It asks a question many (not least Galaxy Quest) have asked before - just how it is that one ship manages to rack up such a high body count of its own crew and innocent bystanders without ever killing the superior officers responsible in the first place? While Scalzi wryly pokes fun at the plot holes and hand-waving science of cheap SF TV, that's not why his book exists in any necessary sense.
Redshirts is really both novel and meta genre commentary in the tradition of, say Northanger Abbey. The more profound question it poses, in its amiable, undidactic way, is why much bad science-fiction (and its kissing cousin, bad fantasy) considers the mass death of unnamed characters to be an essential part of the drama.
Redshirts' target is the use of death as a cheap authorial trick to heighten the spectacle or raise the stakes, and the implicit devaluation of life that results. It's hard to say more about what happens next without invoking spoilers, so let's just say that things get more than a little meta - not to mention increasingly moving - and leave it there.
Almost gone before you know it, Redshirts is a humane piece of work which grows in the reflection. It might not be a typical award winner, but science-fiction could do a lot worse.