Yes, such an accurate description of how well-composed the score for WALL-E really is! Most of my students did not realize there wasn't dialogue either until I asked them to reflect on it. I have never thought about the impact of silence in Cast Away, or any other movie. I think we are trained to hear, and there is so much sound in our world, that unless you stop to think about what you are hearing (or not hearing) the impact of sound simply does not register in our consciousness. Probably exactly the characteristic of human nature that allowed WALL-E's creators to insert music instead of dialogue without us noticing. 🌱