There is really no rhyme or reason for all these petty, Pharisaical little laws. The governing body just wants their followers to be different for its own sake (i.e., they want people to dress, groom, and act in a certain way just because).
When I emailed my JW friend a year or so regarding the spandex (“spankx,” or “spanks”) thing in Anthony Morris’ infamous tirade, my friend replied by saying something to the effect that ‘God’s people should stand out as different, just like the Israelites, who were required to wear a blue thread along the bottom fringed edges of their robes’ (or some similar wording). That goes to show how JWs become hard-wired to just accept any and everything coming down the pike from the governing body – just because.