Women in western society fought long and hard not be segregated, hidden away, and to be given equal rights with men. This hasn’t quite reached its fulfillment, but it is close. Now if we start allowing the option for hiding women, and perhaps more, under the pretext of religious belief, we start undoing the progress of equal rights and introduce relativism that allows an argument by such cultures as Saudi Arabia to say that even by western values, our right to suppress women is a religious right that even they allow. This slippery slope is too obvious to ignore.
Stopping a woman from legally wearing a garment of clothing may make it harder for men to control them, but it also takes the control of their wardrobe out of the hands of the women, too. Having a ban on articles of clothing is just as bad as having a rule that stipulates that they wear them. Both involve having someone telling women what they can and can't do, so neither are good.
Since the Burka and Niqab represents some women's religious and social beliefs, banning them is taking away from their freedom of expression. Women equality means allowing women to express themselves socially the way they see fit. You can not strip someone of something that may see as a part of their belief system and tell them you are protecting their rights.