I think it was a better fit at Universal anyway. HP is geared towards older kids and I think that's a demographic that Universal targets well. I also think it's easier for Universal to build rides that are more intense and may need a higher height requirement. Disney has so many families with younger kids that would get left out.
I know it's been mentioned on this board many times but I'm SO surprised they didn't go with Star Wars land over Avatar. Ride opportunities aside, I'm thinking about the merchandising they are missing out on. The Harry Potter merchandise at Universal has made them incredible $. Wands, cloaks, t-shirts, butterbeer ... when you walk around Universal you see it everywhere. I'm still trying to figure out what on earth Disney is going to create for Pandora!