Here is what I think. Maybe, some women in Islamic societies want the hijab banned because they believe that too many women are forced to wear it, and if it is made a choice, there still will be some people forcing some women to wear it against their will.

I am of the opinion that everybody has the right to decide for themselves.
It gets difficult in societies where some have power over others and those can't make the choice they wish to make out of fear or other reasons.