The problem isn't just about the individual. There's a difference between individual rights and group security. Basically, the burqa has three major drawbacks to it. Firstly, it can demean women, which is more of a societal impact. Secondly, it provides a security risk due to lack of vision to the face. Thirdly, it invokes racism moreso than anything else. I'll give the example of Quebec in Canada, which is intercultural. It banned the burqa for those reasons, and a major reason was because people from foreign countries have to be integrated into society. If you create these differences, racism will become a much more prevalent threat to the individual, especially in a post-9/11 world.
To the second point, that's fairly self-explainable. Concealment of the face is always going to be a safety risk.
Lastly, it demeans women, which I was building on earlier. So, basically, if they're born into the religion, they choose to follow it with their family, whatever. They now can't leave the religious group because they may be socially ostracized. They have to wear the burqa because it's a moral expectation, so if they don't, they'll be socially ostracized. The burqa is a representation of women being demeaned because of a religious text that implicitly states they're inferior. Not only that, but the problem is more wide spread because it affects women in general and not only provide that image to men but also to women.
I understand about personal liberty, but at some points we have to stop it to make sure the rest of society benefits.