It's not even a question of theme. Universal can make themes work for them.
HHN won't move to the new park. A move requires building a new park with enough flex/empty space to support at least ten houses, which is over an acre of total space. The necessary queues will double that needed area.
The Studios, with the soundstages, tents, and extended queues, can expand up to 16 houses without much headache (aside from queues). There is literally no better place to build a house than the soundstages because of the rigging capabilities that are pre-installed. Entertainment and Operations has no incentive whatsoever to constrain themselves by designing houses for empty restaurants (like they did for Islands) when they have soundstages right there.