Those people really behaved like primitive savages. And to cheat the staff who worked so hard for them is mis-directed spite.
I do, however, sympathize with some peoples' disappointment over missed ports. For those fortunate enought to be frequent cruisers it does not matter too much because sea days are also enjoyable and they can visit that port another time.
There are many people though, for whom the cruise was the fulfilment of a life's dream. They many have have longed to visit a particular port for years. To someone who can not cruise every year it is a slap in the face to give them a credit to another cruise in compensation. They will never get to use it.
So please don't make light of other peoples' disappointment. Well, only if they decide to take it out in the form of a mutiny.