I definitely do not get the no photography concept. I would understand if it were "no flash photography", since I could see how flashes might damage exhibits over time, but not allowing people to take pictures at all just seems like the museum trying to make more money by selling postcards, and personally I'd be a lot more inclined to donate $5 to a museum and get pictures of the things I want to remember than pay $1 for a postcard that probably isn't even of the thing I'm interested in.