I have to wonder if there ever was a commitment, even in the blue-sky phase, of a complete redo of Future World West into a full-on Adventureland or Animal Kingdom-esque exotic setting. It seems unlikely given the general lack of focus plus the already extravagant conversion of the central hub into a more natural setting. It boggles the mind further why there's no direct entrance to Moana from the hub as the thematic inconsistency would be a lot less jarring. Have it serve as the "gateway" to World Nature, like the Oasis area of AK, and that would begin to at least make a little bit of sense.
Back to FW West, I just can't see modern Disney doing a full-on retheme of that scale in addition to the ton of money and time they already spent on everything else.
Perhaps it could have made more sense to put the trees and natural elements they used in the hub in FW West instead, making the area look a lot more like what you'd expect from "World Nature," and leave the hub as it was. Still, there's the prominent architecture of the Seas and Land to deal with, not to mention Imagination still sticking out like a sore thumb. Plus, what ultimate value would there be in taking part of what sets
(or used to set) Epcot apart and turning it into something you already did much, much better somewhere else?
Tweak the Moana message more toward conservation of water (and the benefit for the ecosystem) and it's automatically a nice fit for AK, fitting in visually as well as thematically.
The "theme" of Moana (water! conservation! nature! science! (ip)) might technically fit modern "Epcot" but the placemaking and location are a mess.
The more likely scenario is that it's simply the result of an awkward but insistent IP mandate, shoehorned into the park and designed by committee, made up of individuals doing their best to interpret and follow orders which were flawed from the outset. Which is exactly why it's such a mess.