The hotels in the area aren't Universal.
What it boils down to is that by offering food on-site, you can over-charge and people will pay it - even with an IHOP and other restaurants nearby. There will always be people who prefer to just have a lunch at the hotel instead of walking across the street (and the hotel grounds will be fairly big, too). With 2400 rooms or whatever between the two hotels, the food courts will likely be pretty busy.