I do suppose one could think of it this way:
Exec: "Single IP lands are what the public wants! A whole Cars LAND, a whole Star Wars LAND! A whole Marvel LAND!"
WDI: "So, at this rate, how long do you suppose we have before all available land is used up? Not in years, but in IP?"
Exec: "Well... Hmmm... Yeah, we don't want to blow through all our land on just five or six IP. We've got more and more IP coming down the pipeline. What if the next Frozen is right around the corner?"
WDI: "Exactly, that's why lands should have a theme designed to accommodate a range of properties."
Exec: "You're quite right. Very well then... In the past 16 years since it's opened, none of our studios have created any IP that takes place at a pier, or an amusement park, I declare Paradise Pier useless. So make it a catch-all Pixar land, just like you suggested."
WDI: Face palm