When pressed on the apparent anti-imperialist / environmentalist message of Avatar, James Cameron reportedly remarked, "It's not an Oliver Stone-style bludgeon-you-over-the-head political film but it does have a political subtext."
Subtext? The entire impetus for the (stereotypically insensitive) actions of the mining corporation is their single-minded lust for the (supposedly valuable and ridiculously named) "unobtainium," and this in turn drives the actions of our main characters. Effectively, Cameron admits that he treats the key motivating factor behind all the events in the film as mere "subtext." No wonder so little effort was put into motivating/explaining/presenting in a nuanced/realistic/or even remotely plausible way these actions.
Maybe when Hollywood realizes that motive is not meant to be left to subtext, but is rather the driving force behind any film: that which makes the characters plausible and sympathetic and allows the audience to suspend disbelief, maybe then we'll see something decent come out of Hollywood.