The issue of Hijab has always been a difficult topic to touch on especially given the current scenario where feminists and fundamentalists are both working at extreme ends.
I do not believe that any country has a right to interfere into personal likes and dislikes of people. However, if there are some administrative reasons, obviously, the banning of Hijab may be justified though this seems not to be the case in the example of Turkey or France. Sometimes, it is these diehard fanatics which create an environment where any 'symbol', which otherwise would have been quite 'normal', become a thing to detest and protest against.
Can Hijab be justified if other parts of body are prominent?
The purpose of dress, which a person wears keeping in view the norms of morality, is to purify the soul. How can they attain purification when they are revealing themselves? Diaphanous or skin tight clothes run quite averse to the objective of inner purification.