The idea is that the Yeti is the guardian of the Forbidden Mountain, and while he has tolerated past incursions by respectful explorers in the past he objects to the train line being built up there. The ride shows him literally tearing the train tracks off the mountain and chasing you down.
Pamdora has an overt conservation message embedded in the macro storytelling in the land. The movie was very on the nose and the various preshow elements reference this.
Dinosaur isn't as overt as Everest, the Safari, or Kali River, but it was originally named Countdown to Extiction, perhaps referencing that all species are vulnerable to something.