LOL, I'm 26, and I can just imagine how many Generation X and Baby Boomer runners are fuming over this article (and with good reason).
The line that was spot on from the article, IMO, was "Millennials are more interested in overall health and new experiences than in identifying with a particular activity." Competition, or anything that requires real adversity to succeed, is almost looked down upon by 20-somethings. Our generation is all about the path of least resistance, which is why the HIIT movement has gotten so popular.
Interestingly, I turned to running when I was 24 because, in a lot of ways, I think I was just craving something real. Everything in this generation, from exercise to the way we meet people, is so watered down. I've been 1000x happier and more fulfilled ever since I started building up my mileage on the roads. I wonder if any other 20-somethings have felt the same way.