Many girls/ women get confused by the true meaning of hijab, it is so much more than a fabric to cover your head. It extends to your entire dress and demeanour. To an extent I do agree with what you have said above, yes one should dress modestly and in a way that doesn't attract unwanted attention, this also means you shouldnt raise your voice etc as tht could also lead to unwanted attention.
However the flip side of the coin is who are we to discourage a single good deed, for how do we know which will be accepted? Just because someone does dress 'inappropriately' while wearing a headscarf, we may feel this is an improper representation of islam, but maybe in Allah (SWT)'s eyes this is preferable to dressing that way without a hijab.
Also I can appreciate a we are representing our religion, and this way of dressing may not give an accurate reflection, but society needs to understand they cannot judge a religion on the actions of an individual or a group. Religion is perfect we are not.
Finally, and then I promise I will end my essay and maybe stop procastinating and go write a riveting essay (yawn) I notice a lot of talk not just on here but every where about how a women should dress/ act/ live. Lets not forget, men also have restrictions in islam, but as we are a male dominated region at the top that is conveniently forgotten/ hidden. Just a point to consider. :)