Should We Shave??

Whilst talking with friends over the weekend, the issue of under arm hair came up (yes armpits lol).  I personally prefer the clean shave but one of my friends was of the opinion that there was no need to shave , she argued that we were all brain washed into believing one thing and having our image dictated by popular culture " Why would we have hair if we weren't supposed to?" She went on.
Has society really twisted people opinions on something as simple as arm pit hair? Why is it important for women to shave ? Is it really a matter of hygiene?  If its about hygiene then why aren't  men expected to shave too? Are they unhygienic?

Julia Roberts