Hell no you can't put an age limit on rock and roll! We all enjoy a live show in so many different ways. I love that Brandon Flowers from The Killers pumped the brakes on a recent show in Manchester, England to make sure an older dude that was crowd surfing was ok! Flowers noticed the fan being dropped and had a cut on his head so he stopped the show, went down to the pit and had a quick exchange with "Billy" in person.
I totally think that the band performing has a responsibility to make the sure the vibes of the show remains safe. There is a lot of power they hold being on a stage holding a microphone in front of thousands of people.