There are two issues here.
First, women's freedom to wear whatever they want. The people who think this freedom is more important than other issues, I would like to know how deeply committed you are to this principle. Do you really believe they should wear whatever they want? Do you support bikinis as well? If the women around you decided to wear bikinis would you champion their freedom?
The second issue is more difficult, and it has to do with female oppression. You see, just because you ask a woman wearing a burqa if she feels free and she tells you yes isn't very convincing. Why not? Because we as people adapt to whatever situation we encounter. To someone who's always lived like this it feels completely natural, how would they know that there is another way? See, we know this because we've had a feminist movement. There was a time in the not too distant past when women in Europe were being oppressed. If you'd ask a woman in the 50s whether she feels happy staying home with the children and having no prospects of a career, she would also say yes. How could she not when noone else was doing anything different? But today's women, who have come far towards gender equality, they would reject that "yes" because it's coming from someone who doesn't know that there is another way to live. In fact, they would reject their own "yes" from years ago as uninformed.
People rationalize their own situation, it's what we all do, we tell ourselves that our present situation is the way we like things to be. Why? So that we can avoid depression and despair. It's a defense mechanism.
So now we don't operate under the assumption that it's the women who are choosing to wear these. We claim that it's the husbands, and in general, the cultural norms that have shaped people that way.
So the question is this: Operating under the presumption that ultimately it's men who decide what their women wear, do you think they should be free to order any kind of clothing they want? Suppose you're a male, would you support your male friends imposing on their women what to wear?