Holographic screens in science fiction not only need to be able to project light anywhere in space, they also have to block light from behind the "screen" or you won't see shit if your environment isn't all around dark.
Which, now that I think about it, also explains who rooms are barely lit in a lot of science fiction works.
If companies take one thing away from the Apple design, please let it be that it's okay to give elements borders and highlights and shadows to make them stand out. Only that, please don't take away anything else from that design.