I wonder if you saw all the threads about this on the forum, MovieBob. The place nearly exploded with political debates when the film hit theatres. While I would hardly call the members here average people, it is an example of the many who have taken the political message of Avatar very seriously.
The simplicity of the message was always going to be met with scepticism; Hollywood itself appears to have been close to cynical about moral reasoning until now, if you look at The Dark Knight or Ironman for popular examples. Really, film has changed since the first Westerns and simplistic, bad guys and good guys stories of the past. There were morally subtle films in the early days of cinema, but they were a minority, as this was not perceived as an attractive quality commercially. The audience changed with various revolutions in education and technology, and became less accepting on the outset of cardboard cut out archetypal figures like the lone ranger or Tarzan.
Avatar is a call back to those more idealistic times when the hero in any film could believably start out fighting for the wrong side, betray that side without true moral outrage, and win. It was a risky move critically, and could have backfired if the visuals weren't beyond amazing, but financially a very clever move, because it generated such political heat that the film leapt into the audience with all the enthusiasm and controversy of a heavy metal guitarist. These unexpected nostalgic overtones of the film may have been what lead to greater power in the word of mouth reaction of the first viewers, helping to reach that billion dollar profit.
This film should be celebrated for the clever move against the grain of imagination that it is. And for bringing back real heroes after a flood of anti-heroes, who were getting far too common. I've seen enough guns, car chases, killing and one-liners to fill me up for a lifetime - give me more leaping from the back of an insane flying alien to another, bigger one, to make it do as you say. Entertainment-wise, reality can only go so far, and movies like Avatar bring us back the fantasy and legends that modern, less religious, educated humans need.