I think it's a bit like the Old Testament vs the New Testament. If you just look at the Quran as some sects do, the only women who need to cover their faces are Mohamed's wives because they're way hotter than average women. If you read and follow either ahadith texts, books any old kook could have written, then you're going to believe any number of human interpretations including "tagging and bagging" your woman. I think the final arbiter are the women who wear them. Seems like most believe it makes them super muslims.
http://www.thestar.com/news/canada/2...r-a-niqab.html