Director James Cameron is complaining that the Motion Picture Academy did not consider the stars of Avatar for awards in the acting categories. There is already some arguing going about as to what extent the film should be considered an animated motion picture…and I have no opinion on that because, first of all, I haven't seen it. I may not, in fact, because folks keep telling me, "You simply have to see it in 3-D to get the full impact," and the hypnotic power of 3-D puts me to sleep. I also think the argument of whether that process is animation or not is one of those semantic battles that hinges on everyone's particular definitions.
What I wanted to point out though was that the Oscar folks have a long history of ignoring acting performances that seem to be heavily-assisted. If an actress is dubbed or an actor is heavily stunt-doubled, that loses them points. If heavy make-up or special effects seem to be doing a lot of the acting, they lose points for that, too. There are exceptions to this but generally, Best Acting awards go to actors who seem to have kinda earned them, all by themselves. This is one reason why action and fantasy films don't garner a lot of trophies. It's because those roles are often full of stunt-doubling and camera trickery that contribute to the performance.
There may be a solid argument that in Avatar, Sigourney Weaver is "acting" her role just as certainly as she acts any roles she plays. But you can't argue that when we see her performance, we're only looking at the work of Ms. Weaver with the guidance of Mr. Cameron. There are a lot of other people making that character like that…enough to make it feel inappropriate for an award that honors individual achievement. I'm not saying that's right or wrong. But I think that's how it is.