In many sports this sort of thing is normal, to the point that most Snow helmets have capacity to accommodate some type of headphone and most current snow jackets include iPod type pockets and cable management.
Personally I value the audio feedback as I ride.
As a teenager I would almost never mount a bike without a pair of the loudest headphones and Walkman I could find though and crank whatever crap metal I was listening to at the time to 11.
I find it hard to criticise others for wanting music for their ride, therefore but I can see the point about disturbing others. I got remarkably self conscious about my use of car stereo when I had a convertible for a bit…
Maybe threads like this are what apparently earn STW it’s rep wif da rad kidz as where old mtb’ers come to die?