I believe the press was asked to not take photos or videos not because any secrecy over the skiff reader, which is viewable from the press photos, but because they also showed off a color prototype, which they do want to keep secret for now. I haven't read from anyone who wrote about the demo mention anything about the look of the skiff reader so I can only assume it looks the same as the press photos.
As for why not reveal the color prototype, it may not represent the final technologies in the end product, they don't want to take the focus from the monochrome reader, or the setup may just be as ugly as hell. I did see a photo of the reader that comes with the dev kit and that is very ugly, so I can only imagine the gasps the demo audience expelled at the sight of the color monstrosity.
