I've never heard anyone going on about "more depth to the 3D" in Avatar. Quite the reverse, most people who liked it seemed to appreciate the fact that this was a 3D movie that didn't resort to any of the regular 3D cliches (hanRAB waving in the foreground etc,) and actually used it quite sparingly.
I agree Toy Story was a game changer, but, as Spielberg himself has said, Jurassic Park was just a development on the technology established first in The Abyss and then in T2. That James Cameron, he gets everywhere...