It isn't necessarily ok, just that every generation does it.
The Baby boomers did it more than anyone else.
Most of what defined the era was based around sneering at the viewpoint of their parent's generation and what had gone before.
Personally I don't feel the sneering is unfair.. as we all get older we become less relevant, the current zeitgeist means less and less to us.
Laughing at an oldie sayng "you should have more respect young man!" has been undertaken by each generation since time began
It was a bit different...