I would Imagine that if the visor stuck out far enough and the light was aimed at night on a white garage door/or wall-- for the proper height, it would focus the upper beam of light down more to the road, instead of just going up up and away, (pun intended ) Thus giving the rider better road visibility at night. but as short as the ones that I am seeing here are, they must be purely ornamental, they are just too short to direct any light beams down, for better road visibility.
My 2 cents worth