I'm the same, I don't ride with headphones... for me the idea of it is just strange, I enjoy riding my bike, I don't need anything to distract me from that.
I also run (badly) and i know that heaps of people run with headphones (funny, I had only ever know one person that rode with headphones before and that was back in the early 90's, didn't realise so many peopel did), but I never have. I am struggling with the heat here in qld, so lately all my runs have been on the treadmill, and was thinking, its so boring, I may try it. Hated it, I guess I am so used to running with out them for 25 odd years I can't do it.
I always thought that the increase in use with runners is the amount of people that started on a treadmill and used them as a distraction (casue damn the TM is boring) and needed them out on the road, but now I'm thinking maybe people are just so used to having an mp3 player, that it's 2nd nature to them?
How many people rode (for some time) before the influx of ipods etc and now use them all the time vs the people that had mp3's before they started riding?