Not only is it annoying & distracting for the audience trying to view a show, but it truly is dangerous for performers on stage ~ especially on a cruise ship that is constantly in motion. I am glad to see they are enforcing it.
My DD noted this on our November cruise. She's a dancer & finds all the flashes from the audience can be blinding & sometimes impossible to see marks needed to hit during a performance. She said not only are they dancing on a moving stage from the motion of the ship, which must be hard to do, but in several shows like Hercules & Disney Dreams the floor opens up. If a performer is blinded by a flash, they could trip, or fall in, as the stage isn't that big when filled with moving performers. You need to look at it through a performer's eyes ...
ThreeCircles is correct about the intellectual property infringement. A few years ago we were in the audience viewing a performance of Phantom on Broadway. We had these yahoos behind us taking pics with a flash constantly in the first few minutes of the show. Two ushers came down the aisle & said very nicely to either give them the camera, which they could pick up after the show, minus the film, or they could be escorted out & be subject to arrest due to intellectual rights infringement. They did not have the Producer's permission to take pictures. During intermission this couple was arguing with Security in the main lobby about the film in the camera, as they had other pics of the city on it. Security was saying their no photography policy was clearly posted and communicated before the show & in the Playbill. They offered to have the film developed at the couple's expense & they could pick up the pictures the next day- the Phantom shots excluded, or they could mail them the non Phantom photos to their home address. We thought they handled very well. Firm, but nicely. These people grumbled like crazy, ruining the show for everyone around them. We wished they did escort them out...
It always amazed me that Disney would tolerate people taking pictures in shows, especially with flashes,with virtually no enforcement at all... KUDOS to the enforcers...