Larger cruise ships have become destinations as you are essentially sailing around the ocean on a ship that is the equivalent of a large resort casino in Las Vegas. This is a must, as once ships reach a certain size, they cannot dock at many ports.
And while these mega-ships have more to do than you can fit into a week-long cruise, passengers still want to make stops. This is a challenge since only ports like Nassau and Cozumel—destinations for which many frequent cruisers stay on ships—can accommodate many large ships at once.