Because less information = more meaning
Animation takes advantage of quirks of human perception. Good cartoons lie somewhere between nature (no abstraction) and text (full abstraction).
At its best, animation does what live action can’t. Good animation is unrealistic. This starts with the style itself: drawings and designs of things that can’t exist in the real world. Exaggerated heads and hands, huge or tiny eyes, rubber-hose limbs, cubism. A handmade line drawing of a robot requires our uniquely human imaginations to understand it as “a robot,” but we may recognize it more quickly than a photograph of a real robot.
Live action satisfies our voyeurism, animation ridicules it