Few people seem to care about the characters or the plot and this is why I think it'll never leave a deep cultural footprint.
I think you're confusing "nerds" and "people".
None of the characters in either movie are "nerd bait" nor particularly likely to appeal to intellectuals or academics (so that's 90% of columnists and the like out right there). On the contrary, they're total normie-bait. They're mostly straightforward and relatable characters.
But thinking no-one cares about them is a failure of imagination of the same kind as thinking no-one cares about Jack and Rose in Titanic.
I will say the second movie does move a bit beyond the first in this. But not far beyond.
Looking at the people in the cinema when I've seen the movies, it's fascinating because there was a near-total absence of trad nerds. Like, you go and see GotG3 or the D&D movie or whatever and it's like "Nerd, nerd, nerd, normie, nerd, nerd, normie" and so on if you watch people coming in. Avatar 2? I think I was one of about two nerds there. Almost everyone else was like, normal, often with kids. And of my nerdy friends, how many saw Avatar 2? Exactly 0%. And what was particularly interesting was it was mega-packed, and this was on like, week 3 or 4 of release, whereas I haven't seen, say, an MCU movie that packed since Black Panther 1 on opening night.
Re: watching the movies - they're insanely more effective at the cinema than on home TV and I think this another factor, especially with the 30+ nerd crowd. A lot of us just rarely go to the cinema anymore, and instead watch 90%+ of our movies on TV at home. And neither Avatar movie has remotely the same visual impact or "woosh" factor outside of an IMAX-capable cinema doing 3D. And I say that as someone who thinks 3D is generally complete trash. Like, almost everything I've seen in 3D didn't need to be, and didn't benefit from it. At all. Whereas Avatar 1/2? They do kind of need to be, and hugely benefit from it.
I think it would be dangerous to think of this as an American problem. The UK has it's own share of people who are outraged over any depiction of the British empire as anything other than a good and noble endeavour.
I didn't suggest it was an American problem.
What I'm saying is that there's a large section of the
Western populace who is fine with say, colonialism (or in some cases outright racism) against Native Americans (or other indigenous peoples who were more tribal/nomadic rather than city-builders) being depicted relatively positively, and Native Americans being depicted as barbaric, but who is outraged if colonialism against, say, people from the Indian subcontinent is depicted positively, or people from there depicted as barbaric. It's a fascinating and reliable double-standard. It's most extreme in the US, where you even have some fairly far-left PoC activists who are happy to sneer at Native Americans and to try and keep them out of discussions of racial equity and so on (though I understand that is an issue with complexities of its own).
The "colonialism must always be positive unless other people than the British are doing it!" crowd are separate from that and have limited overlap with it. Ironically my experience is that they're slightly more likely to be sympathetic to indigenous peoples, albeit only because they have a tendency to see them as "free" or "natural" in some kind of concerning/fetish-y ways.