The appeal escapes me. It's a cartoon in literally every sense of the word, and not a very good or realistic one. And here I thought Ralph Bakshi warned us about the dangers of humans having sex with cartoons...
Also, do not forget these trusty James Cameron tropes: the myth of the noble savage, the superiority of Neolithic civilizations over advanced ones (in every conceivable way), the innate spirituality that ultimately converts the confused idealist, ... and of course, a fight between a guy/gal in an exoskeleton and a powerful Alien.
Dances With Smurfs...LOLOL
The rest is totally true.
Speaking of Bakshi, should we mention American Pop or other in the genre?
Heavy Metal?
I love rotoscoping.