I love Yusef/Cat Stevens. One of the truly great songwriters. I'm a big fan of early seventies Elton John output. I will defend Debbie Harry to my dying day, as perhaps the greatest ever female front person to a band, and with more than enough credit in the bank to last a lifetime.
Festivals are events to celebrate the known, with the widest possible appreciative crowd. They are by definition for music that's over the hill. I don't get the critical appraisal. What were you hoping for in a field of hundreds of thousands?