Disney doesn't want to rake in free money on IPs that they'll literally NEVER use in their parks for HHN. Why would they want to continue raking in free money on an IP that I could very easily see them using at DHS/DCA? A Simpsons themed area would be a great replacement for Hollywoodland, for example.
Plus, even if they didn't build an attraction, there's a lot of money to be made in merchandising and F&B with the IP.