^ Well, I personally dont know exactly why, But it's probably just one of the rulings that we dont know the reason of and we just take it as how the Hadeeth comes, when Rasulullah peace be upon him said " Wa laa tantaqib al mar2ah wa laa talbis alqoffaaz " And the woman should not wear the Niqaab and she should not wear gloves.

But we know in the hadeeth of Aisha she said that whilst they were in Hajj, whenever they saw a man approaching they would pull their khimar to cover their face until he passed.......but ofcourse that's impossible in todays situation
I'm sorry Ukhti I wasn't much help