You are absolutely right about the attendance declining and spending going up. That is absolutely Disney's plan. This however is not the case for Universal. Disney has a much more comprehensive suite of parks to go to. You can easily stay at Disney for a whole week and go to a different park each day. With Universal, there are only three, so it's more like a weekend destination. Because of that fact, it is imperative for them to come up with another park. They need it to become a week long destination, not a weekend.