Like 80 % or more of all the movie are either general story repeats that you can easily deduct or based in books or comics etc that before you go to the theater you know a good % of the plot. The thing here is that in my opinion is that after taking away the no so what original movie (story), the buzz created because publicity and the people that went for the technology still beat the other as the one people wanted to see.
That is the offense to say something is better and have no merit for it. Plot wise Hurt locker is no more original than Avatar, ironically it is or will be sue because of that also. The 14.7 M that has made as of today (starting late june) is 2% of Avatar domestic box office (if you include international huhhhhhh) and that nunber decreases even more with time. I think there are documentaries with more box office than that. I am also not a hard fan of James Cameron, personally when I watched Titanic I was one of the people thinking that the stupid ship took forever to sink, but I have to admit that even so that I knew how it was gonna end everybody knew, I did not walk away so I give him credit for that.
I don't see any category except for it to be based in reality that the hurt locker will win over Avatar. Either they are the same as many other or Avatar wins. Is the lack of respect to the public which I found offensive. Whoever voted for this can say that they disagree with the public and that is fine with me but the problem is that normally what they say is that they represent the public. If they say "no matter that the people enjoy Avatar more, we give the prize to this one because it is our decision (cojones)" then that is fine.