But they're not as cowardly with their ninja masks 
What those women are wearing are nijabs or face coverings. The coverings many female Muslims wear vary from head coverings or Hijabs to those I have mentioned which cover the face to the infamous burka. If a Muslim woman in western countries is wearing such things, they are saying she is an observant Muslim.
I am not one to generalize ethnic and minority groups. However many Muslims even in the west want secular man-made laws and the equality for all under the law replaced by Islamic Sharia law. Under sharia law, non-Muslims and women aren't equal in the law to Muslim males, out of those people who want sharia law to replace secular law. There are some who are prepared to wage war or commit acts of terrorism to achieve these stated aims. Al Qaeda is the most famous of these organizations fighting for implementation of Islamic law at least in the Islamic countries.
I will make no bones about it, but the Islamic fundamentalists are far worse than their Christian counterparts. That has to do with Islam having a set of god-given religious law, rather similar to the Talmud in Judaism, however Muslims are used to being the ruling class rather than the ruled class (like the Jews have had to experience). That meaning in the Islamic world there has never been a strict separation between the spiritual and secular authorities, like there was in the Christian world.
Mind you my opinions about Christian and Muslim fundamentalists are also a result of myself being a straight male. I am not affected by christian fundamentalists bashing homosexuals. While as a non-muslim who is willing to defend secular law and the equality of all before the law, I am in the trigger hairs of the Islamic fundamentalists.
phobia.