Disclaimer up front: I haven't seen the movie, so I could be wrong on some points. But from what I've heard, Avatar is a movie where:
1) A white man
2) from a technologically advanced civilization
3) who doesn't think much of the less advanced "savages"
4) winds up spending time among them. Although
5) they are suspicious and/or contemptuous of him at first
6) he gradually grows respect for their culture
7) and in turn wins their respect by assimilating their language and customs,
8) even falling in love with a member of the tribe, whom he sexes up. However
9) the militant society to which he belongs is threatening to invade his new tribe and
10) his loyalty is now either divided or entirely shifted.
It doesn't matter whether its meant as an allegory for specific events or not. The point is that by embracing all these cliches, Avatar fits snugly into the Honkey Gone Native rubric.
That means if you've seen any of the movies people keep comparing it to, you'll know from before the opening credits what the narrative arc is going to be. Plus, because Cameron chose this particular archetype, it brings the social baggage of those other movies for anyone who's inclined to notice that stuff (or to drop phrases like "cultural appropriation").
If Cameron had made a movie about an ageing insectoid alien who had lived his life as a burglar and was planning one final audacious theft of a shipment of Highpricium before he retired underwent metamorphosis and entered the final phase of his life, everyone would immediately recognize the story, and know what to expect. I'd actually prefer that one, because heist movies usually don't have pretensions of being social commentary.
Plenty of very good films follow the conventions of a genre, but nothing from the reviews suggests that Avatar has anything in the way of writing or acting to rise above predictability, or that the new technology adds anything other than very realistic images of an alien world. That's an impressive achievement, and they have Oscars specifically for that kind of stuff. You know, the ones where the time limit on acceptance speeches is strictly enforced.
