Also, as with any first movie in a series, it had to spend a lot of time establishing the “universe,” which in this case meant setting up the wonders of Pandora, showing why humans were on that planet, the technology in the future, etc. Now that that business is taken of, the next movies have more freedom to travel through new territory and go even crazier with certain elements.
Although 2009’s Avatar was a visual effects beauty, it was followed a fairly cookie-cutter plot formula, harkening back to Pocahontas and Dances with Wolves.
While this doesn’t provide any new information regarding what any of these upcoming Avatar movies will be about, it is somewhat comforting to know that they won’t feel as constrained as the first movie.