It occurs to me, in mulling over Mockingjay (and my reaction to it), that the book makes a little more sense, and makes me feel better, if I think of it as a revenge tragedy in the best Jacobean tradition.
Because I think Mockingjay IS a revenge story, since I think Katniss is motivated largely by personal and/or selfish reasons - and most of what is selfish or personal to Katniss has to do with the people closest to her. She wants revenge: for Rue, for all the tributes, for Wiress and the morphling addicts and Mags, for herself and the Victors who have to live with what they've done, and what's been done to them. Her mission against President Snow is almost totally one of revenge.
And the classic revenge tragedy can really only have one set of outcomes: deaths. Lots and lots of deaths.
Which is precisely what Collins gives us.
So: Mockingjay = Jacobean Revenge Tragedy.