Are you sure?
This is the claim of the most reactionary. It is disputed, and indeed, the Qur'an is pretty vague on this. The verses in question say something to the effect of covering that which is normally covered, with few specifications as to what that might be exactly. The details are in the Hadith.
Thus, there has been considerable variation across the Muslim world -- with the most famous example probably being the Tuareg of the Sahara where it's the men who go around with only their eyes showing. In SE Asian Islam, women traditionally have worn only a loose head covering and that for formal occasions such as weddings, etc., and a full prayer dress for prayer times. That loose head covering shows plenty of hair, something deemed a no-no by latter-day Islamists, and historical photographs show that women in preparation for bath or around the home would wear a sarong tied to cover the breasts, showing plenty of shoulder, and a bit of leg.
But the point that such patterns of dressing pre-date colonial rule is well-taken. Just that it might be also be noted that in parts of the world where women used to go around topless, it was colonialism that made them cover up, and latter-day modernity that teaches them to selectively disrobe for the benefit of the male gaze.
kj khoo