Actually, that thought passed through my head too.
With the fucking JIZZLOAD of money that they probably spent on hiring (probably) every modeller/texturer/particle/lightning/smoke/motion capture/whatever the fuck artist in the United States, they should've been able to produce a movie which defines a generation (like Star Wars).
If you want to see a well-done animated movie, see Appleseed imo (and Appleseed: Ex Machina, but Appleseed I enjoyed a bit more if I remember correctly).
http://www.imdb.com/title/tt0401233/ http://www.imdb.com/title/tt1043842/
It doesn't have individually modelled leaves which move turbulently under carefully shadered engine wash in a fluorescent jungle, but I'd say the animation is pretty fucking good all things considered - and I'm not sure about this but I don't think it's motion-captured either. It could be though.
I would love to see what a Japanese director could do with an Avatar-sized budget (except Final Fantasy which really, really sucked).