Manners is something you do for others; using socially acceptable customs to denote respect. Does this change over time? Of course it does. But people inconveniently come in many age groups--it does no harm for people of ALL ages to respect each other.
I'm 60ish--I wouldn't dream of going to a rave, and criticizing the activities or manners there.
I guess I'd say, be aware of the context of the event or place, and act accordingly.