Comment by Findecanor

I find that people speaking very loudly into their wireless headsets wherever they are and whomever they are with is a bigger nuisance.

When you speak to someone in person, you'd adjust the volume of your voice to the room and the recipient without thinking about doing it. The engineers who built the analogue phone system were aware of this effect, and made it so that you heard yourself in the handset's speaker. The engineers who designed the cell phone standards decided to ignore this so they could do more echo-cancellation.

It is not a big problem when people are speaking into a slate-shaped cell phone, but when people wear headphones that attenuates their own voice, they hear themselves less and speak extra loudly to compensate.