I don't believe Disney knew what they had, Frozen went through development hell and was pretty much thrown out there once it could be considered done from what I can recall. I remember Disney Infinity back in the day only had standalone Anna and Elsa figures with no actual Frozen world to play and explore in, they had a few Power Up discs that amounted to a texture for the skybox, floor, and a music track all based on concept art, not the movie. The Disc's themselves also featured Anna concept art on them, not the official renders that every other character had. They were given less content than The Lone Ranger and was on par with "heavy hitters" like Tron. Vertical Integration was rushed and slapdash.
Hence, when the parks found out they had armies of 6 years olds lining the gates to meet Anna, Olaf, and Elsa, they were probably a bit blindsided by it all. Hence why the only Frozen stuff at Disney Parks was temporary or lower tier attractions, or just in marketing for a while. It's why they threw Elsa into her own Princess M&G room as soon as they could find the space, why Olaf was on the marketing for Marathons, Summer Events, and the 24 Hour Events, and why the only Frozen attraction for a bit was the Sing Along. It's all they had the time and resources to do.
So you're WDW, and you
need a Frozen ride, and a surrounding land complete with a gift shop and other sub-attractions. And you need all of it
right now. Building one from scratch would be ideal, but costly and time consuming. But you do have a low capacity, low attendance, thematically inconsistent boat ride in a Norway land complete with museums, gift shops, and food pre-baked in. And Epcot could probably handle the foot traffic that a Frozen ride would be bring in a way that Hollywood couldn't pre-Toy/Star. That's why we never got Elsa's Castle, and why Disney's biggest success of the 2010's is seemingly relegated to get a Maelstrom clone til the end of time.
