A woman's hair is part of her glory/ beauty. Since man is God's glory and a woman is "man's glory", we need women not to be a snare for men ... (too attractive as to distract men) during what is supposed to be a congregation with God, a spiritual experience.
It is true. I used to attend a church that had no dress code. I could go with shorts and a T-shirt and felt comfortable about it. My thoughts at the time (a mere prideful justification) was that God does'nt care what you dress like, He looks at your heart. That's true in one sense. However, I did get distracted looking/lusting at gorgeous women -- not just beautiful, flowing hair, but legs, tight jeans ... hello.
Just a temporary distraction though I did get a handle on it and ignored them. We are suppose to ignore the "glory of man".
" But some womem you know come decked out to put in a show.
So there it is, a snare, a distraction that takes a man's mind off of what he is supposed to he doing, worshipping, communing with and honoring God.
It is an act of humility and respect for God AND consideration for man's utter weaknesses for a woman to cover her glory/beauty.
Still, I can look at her beautiful face. I can imagine Miss America or any gorgeous woman coming in to church, wearing a long dress to her ankles, covering up her head and sitting next to me. OMG, I don't think I would very spiritual that day - woe is me.