For me the biggest problem wouldn't be noise and distraction, but the lack of privacy.
If people were always looking over my shoulder I wouldn't be comfortable having HN open in a window/screen for half the day
if I did use the work computer for personal email, It's not like people are sitting on top of each other and 12pt fonts can be read.
This seems to me like kids and their sense of entitlement. Goof off if you want, all you want, but don't expect the company to provide you with privacy just so you don't have to feel bad about it.