I am greatly against it. Most of the objects are unimportant (empty containers, physical objects you can interact with etc). At the moment the highlight shows you important objects among junk. Highlight everything, and you highlight nothing. It's not like og BG1&2 when the world was 2d map, and all interactive objects were placed there manually and to be interacted with.
D:OS2 highlighted everything and result was, what I liked to call "object diarrhea". Though perhaps, ALT could still show name plates for important object, and give other interactable objects some kind of highlight? Or have two seperate highlight buttons.