I suspect though that WDI set out to design a pleasant landscaping and water feature leading to the Seas. That itself was the goal and they probably decided to do that then gave it a Moana theme (as per IP mandates). I think that someone looked at FW and felt it needed more outdoor natural lush features - we can argue whether that was a good conclusion but I can at least understand that motivation.
IOW I don’t think they set out to specifically build a Moana attraction and settled on this idea/location rather than a dark ride or roller coaster in Adventureland or whatever.
Just like they never intended to build a Rapunzel bathroom versus and attraction They needed more bathrooms and slap Rapunzel on it
True as I believe these statements are, they speak to a fault in the contemporary Disney design process.
Moana and Rapunzel are both significant features in the newer Disney Animation catalogue. It's a squandering of the film's potential, a disservice to the guests who love them, and even a missed financial opportunity when Disney takes this backwards-facing approach to conceptual design. No reasonable guest sees Rapunzel's Tower down the Fantasyland West Corridor and assumes that must be the RESTROOM.
You only arrive at that conclusion when working in the direction described above - we have a very basic need in the park that must be filled, let's do a slightly nicer version of it, and we'll slap a popular character on it for extra sizzle. But guests don't percieve the parks that way - the sizzle fizzles when you realize guests see it the entirely opposite direction. "Hey look, Rapunzel's Tower! Rapunzel must be there! Rapunzel's our FAVORITE, let's go! Wait . . . it's . . . Toilets??"
Of course, take a poll and basically anyone would say that a Rapunzel-themed restroom would probably be better than a "generic" restroom . . . but that's not the question in the guest's mind when they encounter these things in person. If you see Moana on the sign you're gonna get excited for Moana. Guests aren't gonna look and say "compared to the non-IP-branded landscaping/water feature/splash zone(?) area they COULD have built, it's nice that they added Moana on top!", they're gonna say "Wait, I was promised Moana, and THIS is all I got??"
This is one of the big areas that WDI seems to have been struggling with in the last decade+ - setting guest expectations. They have to manage the hierarchy of visual cues. Compare these two photos - at first glance, which one looks more like the entrace to an actual ride vs. the entrance to a more basic facility?:
I couldn't even find a decent Nighttime shot of Peter Pan's Flight, which maybe suggests something about how much visual draw the building has. Meanwhile there are literally hundreds of the restroom next door. With its dramatic lighting, glowing lanterns, and literal Tower it practically begs for your attention at night. Yet it heralds no meaningful experience once you arrive.
All this to say, if Disney's thought process around Journey of Water was that they wanted to heighten the impact of the landscaping around Future World, and even go so far with is as to consider it an attraction, they should be free and even encouraged to do that. BUT, they should exercise better judgment than to tack SUCH a hugely popular character onto it, since associating it with that character will alter the guest's perception of the level of the experience. People will expect more from Moana. Journey of Water might be its own pleasant surprise for the guests that way, instead of likely feeling like a throwaway use of a popular princess.