Body Hair -- Adulthood
Body hair is a sign of adulthood. Pre-pubescent children rarely, if ever, have body hair. If a pre-pubescent child does have body hair, that is likely a sign of some underlying disorder. In fact, pubescent means hairy. Body, pubic, and underarm hair supports the body's natural cooling system by wicking sweat away from the body, thereby facilitating evaporative cooling.
Why mess with any of that?
Since moving to my place in a rural area, I live naked 24/7, inside and out. I no longer take a daily shower and only wear deodorant when I put on clothes. I jog every morning and I've found that being hairless, I tend to have less body odor. If I do work up a sweat, I just hose myself off outside. The only "problem" I have is an occasional musky smell from my foreskin, which I actually enjoy.