Incorrect enterpretation. If you want someone to take on great challenges, they must first manage small ones well, lest they fail and give up.
The book above is still somewhat long and challenging, but is more surmountable. It may yet open the door for some to tackle the heavier, dryer works.
Okay, yes, true, but they also constructed the entire N'avi language, created a fuckton of lore about the planet, and thoroughly fleshed out the lore and design of Earth and its voyage to and from Pandora.
This wasn't a visual feast made for the viewer, this was a feast made to employ all these skilled artisans in a massive production, and EVERYONE except the writers fucking blew it out of the water.