I've been around for all of these. I just smiled when the Agile crowd came in. But I have to say, the Agile crowd was the most condescending. Every year Agile finds new LEAN and Earned Value concepts to incorporate into Agile, of course with new names. I do believe Agile emphasized valuable practices, but honestly, under waterfall I met with my customers at least monthly. Why? Because they were paying for it and they wanted to make sure I wasn't abusing their WPI numbers.