What you said about loyal Princess cruisers is just what I found as well. Years ago I was on a Princess cruise and I thought the food was bland - and I mentioned it to some people we were chatting with, and they were loyal Princess cruisers.
Princess can do no wrong for these people, and kudos to Princess for having such a loyal following. These folks love the food just the way it is. One said "I like that I can spice it up myself and not have a chef deciding what I want".
I have often been surprised to see how well Princess does with loyalty and then wonder why Holland America tooks several years to get even a basic loyalty plan in place (they are sister companies).