I just turned 50, and here in the DC area you see a lot of shaved legs. Frankly, I don't care what other people do, but I generally shave my legs and keep them shaved from April - October. It's bad enough running in hot, humid weather and also be itchy and even less comfortable because of hairy legs. I don't give a hoot what people think about it. My wife and kids could care less.
Frankly I've never understood the whole "hair" thing with the millenials -- beards and all. Never had a beard or mustache and never will. And if/when I start losing my hair significantly (I'm lucky to have a good head of hair still), I will not hesitate to shave my head as well. I just don't fancy having bald spots or thin hair. I just could not stand training with long hair and a beard -- eek.
To each his own...