Because this would be at least 5 times slower to transfer compared to regular image formats, and on mobile a lot of energy goes to power the screen (while user

Because this would be at least 5 times slower to transfer compared to regular image formats, and on mobile a lot of energy goes to power the screen (while user is staring at a blank one, waiting for data) and radios (which now have 5x more work to do). JPEG XS has severe restrictions of realtime encoding and a 30-line buffer, which are necessary for its goals, but make it a bad choice for anything that doesn't have such limitations.