I'm not saying people didn't 'switch sides' so to speak, but you cannot under any circumstance just dismiss punk as low class trash. A lot of now-metal bands started off as punk acts, and some punk records are amongst the best of all time.
Punk has done nothing but breed crap subgenres like Emo, Hardcore, and Pop. The old punk bands were more respectable than todays candy pop punk. People can like punk all they want, but you won't find me at a punk show. I think there will be a resurgence of punk when all the great metal bands are gone because people are getting dumber and dumber and most kids from the next generation are lazy and don't respect music.