The answer is not as simple as the analogy suggests, but the principle of the problem is that the conflict resolved by the rat driving the human around is centr

The answer is not as simple as the analogy suggests, but the principle of the problem is that the conflict resolved by the rat driving the human around is central to the theme and the characters, while the dog flying the airplane is not. I used to have a high opinion of Up, having originally seen it when it came out in theaters. It was only on a re-watch that I was shocked by how much of that opinion was based on what is essentially only 15 minutes of the total runtime. Ratatouille is fundamentally about a ratty artist overcoming his background and prejudices. Up wants to be about an old man managing to move past his grief, but the climax (and most of the movie) involves a stupid bird and a stupid kid that only detract from the experience.