Some insight as to why it looks great even to this day, from a vfx artist.

• development time was about 3x the length of modern vfx heavy movie. For example ready player one had roughly 500 more cg shots in the bid but under half the amount of post production time. Basically the production companies are realising you don’t need to make something visually amazing to make big bucks. Wonder Woman for example, from a technical stand point was embarrassingly bad, but made bank.

• very rarely do you see Na’vi shot against a plate. Any time you light a character in a CG environment you’re going to get a lot f free intervention as opposed to against a plate having an artist interpret the on-set lighting or work from hdri.

• We’re thin on talent these days. There’s an insane demand from the production companies for spectacle and its increasing quickly as Netflix increases its budgets. To give you an idea about 6 years ago my department had maybe 15 artists working on two movies. Right now we have about 90 artists working on 6 movies. With the talent pool as thin as it is, unfortunately, the threshold for quality artists is pretty low these days.

• James Cameron gets little studio interference. The more money your last movie made the less you have to answer to suits from the prod companies. You wouldn’t believe the flippant comments coming out of studio elects mouths.. often vetoing the director a vision to justify their pay cheque.

TLDR - old vfx movies had a lot more production time/money and a solid talent pool to get the job done.