Because "you have x minutes left at your current level of cpu utilization" has always been implied. If user have forgotten that, it's no reason to remove it.

Because "you have x minutes left at your current level of cpu utilization" has always been implied. If user have forgotten that, it's no reason to remove it. In fact there's rarely a reason to remove a feature if it doesn't cause issues. Taking your own exemple of video rendering, if I begin a render and After Effect (or similar) says it will take 50 minutes to render, but the remaining time says I only have 20 minutes left of battery (implying "at the current load"), I know I have to charge my laptop if I want to render the video.