I agree that generalising about different age groups, parents, etc or indeed anyone is not necessary. Everyone is an individual and nobody likes being pigeonholed. Just because some people of a certain age group has done something on a particular occasion doesn't mean they all do. It just happens to be you notice those individuals at that time. On the other part of the ship you don't see others of other age groups doing the same. Probably the next day or on another cruise people from other age groups do the same etc.
I'm one of the newish youngish people to doing cruises and know there is an incorrect perception about people my age wanting to change everything, have no formal nights, drink too much, etc. When people who think like this talk to me and get to know me their perceptions are challenged.