Mmmm. I dunno. If the service is bad, people will complain, and then you will lose your job.
Take Disneyland, the Happiest Place on Earth. Employees seem pretty happy there, and they aren't tipped. However, Disneyland is very expensive now! I went to a restaurant in New Zealand, and there was no tipping. Service same as USA I thought.
One thing I am wondering though. If the price keeps going up on cruising, at some point it will only be for the wealthy. Maybe that's where this is going.