I think this is kind of a temporary workaround. In Apples ideal world, the Vision Pro would actually be transparent and you could see the users eyes for real, but the tech isn't ready to project what apple is doing on glasses. So they settled for a VR headset and put eyes on the outside. Eventually in however many years it takes, they will actually use glasses and won't have to do the screen on the outside. They must believe, that being able to see Vision Pro users eyes is integral to the product, or at least important to the product being accepted by everyone.