The problem ISN'T the fact that its a story thats been told a thousand times. I mean, its a genuine recurring historical event. And a good retelling of a classic story… is good. And the movie did oh, 70% of it SO well.
The problem is that it was told blandly and with one dimensional characters that had no depth or nuance that were jerks... mostly for the sake of being jerks.
The worst part is, the very end of the movie had the tagline that apparently, Earth was pretty much dead and this was their only hope. If that had been incorporated into the movie just a little more, with say... 2 lines. If every single damn soldier hadn't been AMAZINGLY gung-ho about going off and killing things. (Yeah, its nice that pilot chick turned sides, but she was the only one.) 2 lines before the battle, a slightly different speech than what was given. It would have made a huge difference.
"Sir? Is this right? They are the natives. I think we might be in the wrong about this…"
"No solidier, its not easy. But we must have that unobtanium, or else every man, woman and child on earth will die. I lost my sister to the plauge, and I won't let anyone else die. We tried peace for as long as we could, have wasted YEARS while people back home die, and they have left us no other choice. We'll have to take it by force. For the future of everyone you ever loved, ever will love, and all the generations to come. We must do this."
Except then of course, it wouldn't be a happy feel good ending when Jake turned traitor and started killing his own kind and underwent a magic soul transfusion at the end and doomed all of Earth to... some sort of "dying" fate. You would have wondered if he did the right thing, if it was okay to actually root for him. Instead it was just a ho hum "greed and deforestation is bad" spiel that Captain Planet could have given us.
Seriously. 30 seconds. A slightly different speech. Completely different movie with instantly more depth and complexity and more than one side to it.