Another decade, another most expensive movie ever. And yes, writer-director-world-king James Cameron’s new extravaganza is a cultural milestone, but its flashy technical breakthroughs will be obviated soon enough, leaving behind only the dated embarrassments of some pretty dreary storytelling.

“Avatar” is a complex experiment to determine whether computer-abetted imagery actually can achieve enough sophistication to ameliorate banal screenwriting–oh, and whether that even matters to the bottom line. Answer: nope!

Sam Worthington plays a paraplegic ex-Marine on a distant world whose inhabitants’ bond with nature goes rather explicitly beyond just hugging trees. With help from Sigourney Weaver, as the scientist who lends him an alien body to drive, and Zoe Saldana, as the aboriginal princess who gets him going native, our hero gradually decides to fend off the encroachments of human warmongers and corporate raiders (typified, respectively and cheesily, by Stephen Lang and Giovanni Ribisi). Also, a muscle-flexing Michelle Rodriguez is on hand to affirm the increasing tokenism of Cameron’s so-called “strong roles for women.”

We were promised the future of movies, but narratively “Avatar” dead-ends in the past. Call it Pocahontas Dances with Wolves and Aliens and fellow Smurfish skinny feline noble savages in the FernGully New World, and call it a day. And if you really do want a visionary and sophisticated and actually good movie about besieged creatures living under a big tree, see Wes Anderson’s “Fantastic Mr. Fox” instead.

Cameron’s awe of his alternate reality is palpable. His effects are rendered vividly and seamlessly. But his characters might as well be cardboard cutouts with doodled features, and the story really is just three hours of generic hero’s-journey claptrap and pathetic lip service to exhausted Bush-in-Iraq critique and other callow anti-corporate, eco-advocate politics. All of which is pretty rich coming from a tech-dependent, multinational-financed blockbuster opening planet-wide.

It’s not glib to ask why Cameron even bothered with characters and story at all. He could have stuck to sensory overlaod alone, and just done it as a theme park. As a movie, “Avatar” seems grandiose at first, but less so in context. It lacks the true epic grandeur of Peter Jackson’s “Lord of the Rings” films. It lacks Pixar’s careful balance of classic and cutting-edge. Hell, it even lacks the imagination of the “Star Wars” prequels. The prequels! Maybe it’s not even worth pointing out anymore that technical ambition alone isn’t what made “The Terminator,” Cameron’s 1984 breakthrough, into a crowd-pleasing new classic. And maybe that’s exactly the unheeded lesson that “Avatar”‘s no-going-back hype is meant to obscure.