[imtringued]

Wearing over the ear headphones all day can contribute to cranial pressure, tiring out your jaw muscles and strain your temporomandibular joint.

It can also encourage ear infections and clogging of the eustachian tubes, because covering or plugging your ears slows down the self cleaning process.

At first you won't notice, but after a decade, these problems will slowly creep up on you and fixing them is very expensive, because you're basically slowly deforming your bones.

I personally wouldn't let kids/teenagers use headphones that apply any amount of noticeable pressure.