To me, the times, events, collective mood, current musical atmosphere all influence a band and their music. I prefer to listen to and see performances of musicians in real time. I'm sure there are exceptions to everthing, but for the most part the aged rock musicians are hollow shells of themselves when they originally played. They will never have the drive, the exhuberance, the skill, the voice, the energy, the "hey **** it" attitude they once had.
Plus there are great contemporary bands now making great music who do have all those qualities. I love to crank the first Sabbath record, its innovative, energetic and fresh. But it is what it is. People get older, they get mortgages and kids. They'll never be those 20-year olds again.