Cruising on Cruise ships is a means of travel with some substantial benefits, but a few drawbacks too. The majority of people love them, but some people hate them. Cruising makes it easy to visit several places in a single trip without the need to repack your belongings and sit in a car/train/bus/plane to travel to each one; your hotel room comes along with you, and even provides the transportation.
Additionally, seeing several islands or cities in a region can help you decide if and where you want to visit later for a longer time. Typical itineraries also limit the time you can spend in each place, usually just a short day of activities or sightseeing. They may also include one or more days at sea: paradise if you enjoy a relaxing day by the pool, but frustrating if you prefer more active and open exploration. Nonetheless, the benefits far outweigh the drawbacks for enough people to support a growing industry.