With me, it's just personal preference.  For starters, it makes your dick look bigger....I need all the help I can get! 

  I also don't have to worry about getting hairs caught in my underwear elastic. Plus....as some have mentioned....it's another way of being "more nude".  I love being totally nude. When I'm home, I'm not wearing anything. Totally nude....all the time.  Its just so damn comfortable. If I'm being honest...I shave my entire body.  By birth, I'm a bit of a hairball, so to shave it all off......oh yeah.....it's almost erotic to be totally smooth.