I disagree, I think what you're describing will under-impress on a massive (billion-dollar) scale.
And you're wrong that what I'm describing is a "single IP" land.
To simplify, these are the common approaches to a land:
1. Compendium (Fantasyland, Adventureland, Tomorrowland, Pixar Pier, Fantasy Springs...). All of these have a broadly unified aesthetic, yet the characters/stories are kept separated.
2. Single IP (Cars Land, Toy Story Land, SWGE, Monstropolis). These follow the Potter format.
So the Villains Land I'm describing is neither of these models. It's very much "different IPs" but it would have a context/concept that unified them. Maybe Fantasy Springs is the closes thing but I don't think the characters are intertwined in any way as Villains Land would/could.
If they do a straight up Compendium with no context/concept that unifies them, it will be lambasted as a failure. Too many guests will find it unsatisfying and question why the land even needed to exist (individual rides with these villains can just go in Fantasyland).