I have a several theories about this, some of which have already been mentioned here:
- They don't want to look at their disgusting brown skin.
- The men don't want to have to go to the postbox to post their mail.
- The women wish to obscure their utter contempt for moral beliefs and values.
- The women don't want to be raped by dirty, immoral brown beasts.
- They're easy to spot in the desert.
- The clothing is perfect cover for hiding explosive devices and other muslim instruments of evil (like the qur'an).
- "Allah said so" (aka "the voices in my head are telling me to destroy the west").
- They know it annoys us and they merely do it to get on our nerves and to tempt us from the righteous path to Heaven.
- They are ragheads, what else do you expect?