Speaking of having little story to build on, Carsland is amazingly thin.
It's a mega setting for a road race. A one note Opera but it works. "Ornament Valley" is the same red rock work we've seen at Big Thunder Mountain, only the iconic references are different. The only "story" lies in the personalities of the characters. The area will be very immersive and like being in the film. That is it's power. If you never saw the film, the setting will still transport you. The show scenes in the ride will tell some of the story, but basically the environment is less unique than Pandora, but because it's true to the film will still work.
Cars and Cars2 both survived lukewarm to bad reviews by making fortunes and like Avatar, are very derivative of other movies. IMO the theme of Carsland completely ignores "California", "Walt's coming to California in the 20's" etc., which is DCA's self proclaimed overarching theme. They claim it's "Californian" because it relates to "Car Culture". Yeah right. It's basically NASCAR which is big in the South. TSMM has nothing to do with "California" either, but it's kinda Disney and it's fun so we give Pixar a pass, in fact, everyone is dying to see Carsland even if it does not fit the big idea. In comparison, I'd venture to say Avatar is almost more closely related thematically (or at least a similar stretch) to DAK than Cars fantasy Utah is to DCA.
I think one issue that may be driving this is that Cameron's films, like Ridley Scott, tonally are just not "Disney". They are emotional but lack the sentimental feel that you usually find in Pixar or Disney product. Cameron feels more Universal to me and that's one reason that it may be harder to sense a good fit.
Just something to consider.