While I can get the existential frustration of young children preferring to spend time on playgrounds versus high tech family rides, the reality has always been this way - kids need open, free form spaces to let off steam, especially when theme parks have so much rigid structure in their DNA. When I was a kid, Curious George, Camp Jurassic, The Olive - all rocked.
With that said - Seuss Landing does not need another playground! It already has one! The park was ostensibly designed with the understanding that many of its premiere rides were not appropriate for younger children, so they built *three* play areas, two of them extremely elaborate. (The Olive used to have more to do, but the lawyers decimated the crawl spaces.) I think the kids have enough play areas across both parks, and I suspect Epic Universe will also include sufficient play space between Nintendo and Dragons.