I am referring to the unique twist that Cameron at first seemed to add to the concept of a "living planet", infusing our modern understanding of global ecology and neuroscience into this age-old schema. The modern addition is provided by the concept of Pandora having a central nervous system complete with neural networks with synapses and nodes which pass messages across to each other using a biochemical process much like that of our own brains all centered in a region around the sacred Tree of Souls.
Indeed, Pandora's indigenous humanoids, the Na'vi, are able to forge both temporary and lasting neural connections with animals and (some) trees, through villi in their long hair braids, making them not just philosophically, but literally, connected to their ecological sphere.
This is a most apt modern metaphor for our current understanding of the delicate interconnectedness and balance of Earth's ecological fauna and flora. Here is a world that makes the implicit relationships between all living things explicit allowing us to explore the questions of interconnectedness in new and potent ways using science instead of magic.
For instance, what role do the Na'vi play within the powerful neural network of Pandora? While they can "link" to at least some plant life and several fearsome creatures in order to tame them for hunting and transport, the humanoids are still left using spears with poison arrowheads to do their hunting and protect themselves from harm. Indeed, why do the different creatures of the planet need to prey on each other to survive? Are they not all parts (cells? organs?) of the same body? Surely the living creatures on Pandora are more than the equivalent of our skin cells something that the body just sloughs off to make room for more. The neural network is a marvelous metaphor, but under even minimal scrutiny, it starts to wobble and fall apart.
Even assuming that the Na'vi for some reason are not an official part of the neural system (maybe it's only the trees that are interconnected), shouldn't there be an obvious effect on the vast interlinked Pandora network when some of its trees (including the awesome Hometree) are bulldozed, burned and bombed? Thanks to modern neuroscience, we have a lot of knowledge about what would happen if a part of a living brain or neural network was damaged. Would Pandora react like a person who experienced a stroke, shock treatment or head trauma? Would there be partial paralysis (e.g., the floating mountains collapsing, swaths of the forest crashing down) or would other parts of the brain take over and compensate? Would there be regrowth or permanent damage? Unfortunately, we do not know, since the metaphor again - is not developed or taken to its logical conclusion.
It is true that expectations are the road to disappointment. I was led to expect a spectacularly crafted pro-ecology, anti-colonization flick with solid acting, phenomenal special effects, and heart-stopping 3-D. I must admit I did not feel let down in any of these regards. However, having opened a Pandora's box of promising world-building possibilities, I was disappointed to find out it was just an empty trunk full of the same old magical realism and tribal wisdom.
At the end, perhaps it was just a matter of timing. Perhaps after the inevitable lovers' spat over "betrayal", and the vast and impressive battle sequences, there was simply not enough time left to show the missing neural damage scenes. You know, the ones in which we see that Pandora, stunned and immobile, can no longer connect to the ancestral voices from the Sacred Tree due to the massive attacks to its executive functioning. Of course it's all fixed later on by the Avatars from the science team so I can see how the whole thing might have seemed extra to a director who needed to make some tough choices. Perhaps that is how, when the final cuts were made, Cameron decided that he would rather have a battle in front of him than show Pandora with a frontal lobotomy.