Everest was not created because 'Animal Kingdom needs a yeti ride." It was created because "Animal Kingdom needs a roller coaster. Come up with a theme that fits the park."
Joe Rhode can spin the importance of the backstory and theming all he wants, but even he, at the end of the day, would surely be smart enough to know that the main reason people want to ride Expedition Everest is because it's a roller coaster.
Yes, Everest does, in fact, have a rich and detailed backstory, but 95% of all riders don't catch on to any of it because it's all subtle and exists for those who wish to seek it out. None of it is imperative to the enjoyment of the ride, but knowledge of it is more or less "icing on the cake."
Why is Guardians of the Galaxy at Epcot going to be a roller coaster? Because Imagineers felt that that the story of Peter Quill at Epcot simply must be told and there is no other way to tell this story than via a roller coaster? Nope! It's because it's a popular IP and adding a roller coaster to a park that previously didn't have one will draw in large crowds.