I have heard many times that Disney was first offered the rights to a Harry Potter World, Hogsmeade, and Diagonal Alley, but turned down because the owners of the rights specified that certain things had to be done in certain ways, and Disney insisted on total creative control. So they lost out on a lot, besides allowing a competitor to grow and expand. When they saw how much they lost, they picked up Avatar Land instead. And Avatar made no sense at all for Disney, but, oh well.
The result is that Disney spent a ton of money, and got two whole rides. Meanwhile, people flock to Universal just for Harry Potter World and thousands of them everyday walk around wearing Hogwarts robes. Disney could only wish that Star Wars / Jedi robes were so popular.