(What follows is a rough rough draft of a post I'm working on for OU, responses will be incorporated in and nothing is final. I will remove pronouns, clarify, and put into some logical order.)
We're disagreeing on the average guests' interest in these things. Since day one DAK has had issues with guests going attraction to attraction and skipping the smaller experiences. Disney has tried many ways to get guests into the trails and other non traditional experiences in the park to minimal success. I believe guests are looking for things to do and justify their time at DAK while at other parks (minus DHS) they're entertained till they leave. I think Avatar /ROL will be the attractions people are looking for more like what Mermaid, TSMM, and Monsters Inc were at DCA and not the day shifting experience Carsland/WoC at DCA was. Disney has set the DCA redo as the benchmark for this and it follows a similar model, but I don't think this will match their expectations (despite whatever they say in public).
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Disney's been looking for a very long time to add IP to the park, and in that plot in particular; one of their Harry Potter pitches was for that area. When Universal refused to give Cameron more than just one ride replacing T2 for Avatar, Disney came in and got the rights thinking they got a similar coup to Universal getting Potter.
But then Cameron became demanding, the movie didn't develop merchandise legs, the movie's public narrative switched, and the costs of design changes after bids went out kept adding up. Right now Rivers of Light and Avatar cost a billion dollars. Mermaid, WoC, Paradise Pier changes, BvS, and Carsland cost that much at DCA. Down the street the combined costs of Hogsmeade, Diagon Alley, and Hogwarts Express/London don't add up to 3/4ths of the cost of Avatar/RoL. This isn't Disney spending money effectively and putting more in for a better product, this is them constantly wasting it and not meeting expectations. Rivers of Light got a late game cash infusion because Staggs was not happy with what he saw, saying it was not the project he green lit for way less money.
Over the Christmas holiday Olivander's at USH made over one million dollars in wand sales in a week. ONE WEEK. That's the historic expectation and budgeting Disney has placed on Avatar/RoL projects and no one in their right minds thinks it'll touch that. There are people on here who say costs don't matter but they do; Everest didn't see the return on investment DAK was looking for and as such they passed on several new attractions and lands until Avatar was forced by the Board of Directors. I expect Epcot's additions and plans for the 50th will be hit the hardest if DAK and WDW don't see the returns they want.
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Because I question Disney's justification and expectations does not dampen my expectations. I am excited to see this project open, experience it myself, and develop my own critiques just as I have with Kong, Diagon, Mermaid, SDMT, and more. But we cannot ignore or escape the fact this land is deeply entwined with expectations of Potter level per guest spending boosts, attendance boosts, guests staying longer in the park, and that Disney's "sticking" it to Universal.
I expect there will be fans of this land, I expect people will say they prefer it to Diagon Alley, and I expect some will come for opening day as Avatar fans. I expect the attractions will be fun, engaging, and good. I bet the food will be good, the drinks boozy, and the merch creative. But that's not enough to guarantee continued expansion and updates to WDW.