Of course back 35 40 years ago Those music clubs were packed with 18, 19, 20 and 21 year olds. And there were lots of good bands all playing current music. Selling high profit beer to that demographic who really wants to hear current music was very lucrative.
Things change. Sure it sucks but gosh we can't be Dana Carvey he's grumpy old man.
And even had there been no changes at all in the drinking age I don't suppose the local rock club is going to sell out with 60 old guys on stage playing Train and black eyed peas songs.
Like Apollo Creed said to Rocky Balboa, " It's a shame we gotta get old."

WSS