you woud think they would want to change to a smaller box as it would save them a lot of money..a smaller box would be less packaging and since box is less than halfway full that reduces the amount of cardboard needed formthe box, less ink required for printing on box, more boxes would fit in the box for shipping therefore requiring less shipping as more boxes in a shipping box means less boxes to ship.
therefore in doing that they can substantially reduce cost while not changing contents or price.

therefore the only logical reason to stay witha big half filled box is to decieve consumers.