^It's not fair to blame everything on the media and conditioning, as people do have some sort of consciousness (as least that's what people generally believe).
I think the inscriptivist view of shaving makes the most sense. The perception of arm pit hair in women as unattractive can and has been inscribed onto our bodies. People aren't born a tabula rasa; they are born with certain perceptions and tastes already intact. With the media and societal standards, these tastes are perpetrated.
Yeah, I think people are pretty different about how they perceive their surroundings. Some people see something presented and accept it, incorporating it to the point where reflection is just irrelevant, and others don't readily accept what's presented to them.
Anyhow, some of these things are "programmed" - it's all about enhancing the physical differences between men and women. What are men (as a result of their Y chromosome, and lack of extra X)? Hairier, bigger, smellier - what do women all feel they need to be? Hairless, small, scent-less or disguising their natural smell.
Interestingly, of course, more testosterone gives less fat compared to muscle - so it's a little interesting that women are striving against that hormonal difference. I could come up with a number of hypothesis why that is, but they have a hint of ad hoc about them.