Disney World was not created by one person. Everyone needs assistance. People to bounce ideas off of and to come up with their own.
In places around the globe and even domestically, new material is still being assimilated. The umbrella of themed entertainment branches out into all sorts of media that Disney has under their wing. We talk as if Frozen has been around forever, but it's not even a year old property yet. Introducing it in the theaters was not a guaranteed success. And under the umbrella of themed entertainment, the entire Marvel Cinematic Universe was a risk. A relatively unknown property in Guardians of the Galaxy was just released this month to rave reviews. I think to a extent Pandora is a risk.
Attractions such as Mystic Manor or Expedition Everest display no connectivity to any known franchise. While Disney is complacent in some of their material, the problem isn't the franchises or introducing new material...
Because in the end, the only thing that matters to the paying guest is the execution of the attractions.