Another point to consider is how each new generation of people have exhibited better abilities in visual perception. In tests for being able to distinguish and recognize individual pictures within a second, children are now approaching ranges around thirty separate images. And while the illusion of motion relies on animating frames that are very similar to one another, our increased perceptual abilities as time goes on will still cause the animation of today to seem less convincing as we are better trained to distinguish the succession of images.
Our standards for convincing animation and detail may become slightly higher in the future due to trends like these.