MP3 players

Today I’m talking of something not that relevant, still interesting, that I just re-experienced, and which I am sure will re-experience again.
Have you notice the extreme proliferation of MP3 and other sound devices in society. In Portugal I normally drive, so no big need for MP3 player since I have the car radio, in the UK I am a pedestrian as such I need some music to go from A to B. It is not something I think much about, simply before I leave the house I put on the MP3 player, it's like an extension, a need for entertainment while I walk, or ride the bus, or whatever. No problems so far, the thing is I notice that people talk less and less to each other, I mean the music is like a shield from everybody else (Don't get me wrong sometimes I really like the shield, namely when I meet someone I really don't want to talk to, still they always have a way to break the shield anyway :P).
Today I was getting on the bus and there were 2 other people there, which I am sure we might have a casual conversation, instead we waited for 15 minutes in the cold with head phones on. Not that I am against this, but people do complain that society is more distant, that people bond less, and that those bonds mean less.
The casual conversation in a plane or a train going somewhere, is slowly being killed by the head phones, and actually I meet some nice people in these situations, not people that you keep in touch, but simply an interaction, an exchange of ideas, a casual conversation about nothing to past the time.
I like music a lot, and I learn from it, study it (in a way), but the question still came to mind, aren't we giving up the opportunities of living by closing ourselves in our bubble with pre selected sound tracks and pre selected thoughts? Just a thought.