I really don't understand why the political agenda of a film like Avatar prevents people from liking it. I love The Dark Knight, and that film had very conservative undertones. The way I see it, it's there if you want to take it in, but you can ignore it and enjoy the ride if you like.
I also don't understand how environmentalism is "liberal." It's an issue that affects everyone, and guess what? If we keep going the way we're going, we ARE going to seriously fuck up our planet. Just because you don't like that idea doesn't mean you should dislike a movie that says, "Hey, we should probably think a little bit before we do this shit next time.
And I don't see the "This is what humans do!" line as a Bush commentary at all. That is what humans do. Look at what we did to the Native Americans, or Alexander's conquests, or the Nazis, or any other part of human history.
By the way, I'm not trying to attack you personally in any way. I'm just throwing my two cents in the pile.