People still have bodies
Hands, eyes, attention and fatigue set the limits of every interface and every building. A thumb reaches the same distance it did a decade ago. Low contrast still fails the same eyes in the same afternoon light. Someone carrying shopping still needs a door that opens without a second thought.
Generated work inherits none of this by default. It inherits the average of what has been made before, mistakes included. The designer who understands the body, its reach, its tolerance for noise and the way it tires, holds knowledge that every new tool still has to be told. As interfaces move off screens and into rooms, vehicles and objects, that knowledge matters more, because the body becomes the whole interface again.