It should not be up to us to dictate the dress attire of anyone as long as they are not harming others. If a woman chooses (and I use that word very loosely knowing the dynamic of some Muslim households) to wear a burka, then she should have the absolute right to do so. You cannot be a free country and demand women to dress a certain way. A secular country separates religion from the government, but does not dictate the absence of religion from the people. If a government decides to enforce such law, it will tread a very slippery slope. Where does it stop?
Are you going to ask Jews not to wear yamakas? Are you going to ask Christians not to wear crosses? How about the Star of David? A big red Santa Claus hat?
I am not a defender of any religion, especially one that asks its women to cover their faces, but what I do defend against is: Hypocrisy. You cannot ask the people to follow inconsistent rules and more importantly, you cannot ask the people to follow a dress code. There is a term for that, it is called: Fascism.