Chester and Hester emphasized the value of nature through our widespread commercialization of it (same as Harambe, and same as Animal Kingdom itself, in the real world), even after it's been gone for 66 million years, we're still obsessed with it, that's how valuable it is. It emphasized the importance of conservation through the finality of extinction. It emphasized the superiority of nature through its weathered extererior, as natural forces subjugate human architecture. It explored our real relationship with the species we never got a chance to meet. I could go on.