This all makes my head spin. The way I see it, a theme park is nothing like a hotel. A hotel has a fixed number of rooms and each room has a fixed number of beds. The demand must absolutely be adjusted with price because the supply is absolutely fixed.
Except on one or two of the busiest days in the year a theme park has no such absolute limit on capacity. Park hours can be increased or decreased, seasonal attractions and food venues can be opened and closed, tables, eating areas and cash registers can be opened or closed, live shows can have more or less frequent schedules, and many rides can operate at more or less capacity depending on the number of vehicles and tracks that are in circulation. Extra shows, such as streetmosphere actors, musical acts and firework displays can be added and deleted according to expected crowds. And if the overall product is in more demand then why not just go ahead and make more product to sell. It's not like WDW ran out of land or anything. Or ideas. Or maybe they did ...
Consider this - does Corn Flakes offer seasonal pricing because they noticed that sales are heavier from Nov - April than the rest of the year?
Disney can go ahead and try to push the industry into a direction that makes no economic sense, by pretending that they have to manage theme park capacity as if they own a virtual vacation monopoly with fixed limits on capacity. Whether the public will go along is a completely different thing.