This long article at the New York Times on "‘Avatar’ and the Mystery of the Vanishing Blockbuster," asking why the movie has "mainly been forgotten" takes a lot of words to skirt around the obvious answer, which is that outside of the special effects, the movie is actually quite bad, pretty boring, and with entirely forgettable world building. https://www.nytimes.com/2022/11/30/magazine/avatar-franchise.html
@arossp I disagree with "entirely forgettable world building" but it definitely qualifies for "severely squandered world building".
They had some cool ideas for their world, but they chose to downplay those to focus on the boring sexy blue biped Pocahontas story instead.