Why? It is possible that first-timers at these shows will have a truly enjoyable time. I'm sure they will have an idea of what they missed when Glenn was there, but they can't really know. Ignorance is bliss, perhaps? No doubt there are fans who got to see them in their 70s heyday who feel sorry for those who only got to see them when they were past their prime. Yet the late-day fans still saw a great concert.
I wish I could have seen them live at some point but having seen so much video footage of their shows, it is kind of a meaningless regret b/c I definitely would have preferred to see them in the 70s--and I was too young to go to concerts then.
You may want to feel sorry for those of us who missed Glenn's solo shows. That is something I truly regret missing.