A couple days ago there was a bit of a conversation about this, you might find it interesting. It seems this feeling (to the point of calling it an "epidemic"!) might be caused by the known bias of thinking that earlier times were better:

https://news.ycombinator.com/item?id=46424228

LOL. People not using headphones in public are narcissistic a-holes, but they’ve been doing it since *long* before headphone jacks went missing from smartphones.