For modesty. They cover up for self respect and modesty and believe showing their beauty and body should only be for their husbands and/or family. Nothing wrong with beautifying yourself, but for the right reasons and for the right person. It's not just in the Quran. It's the bible too. If you see old movies and read books they describe any woman back in those days, that she is modest and covered up. If you guys wonder why Muslims girls wear a head piece ( Hijab) or a full body piece ( Abaya) then you must look at Virgin Mary, her head is covered in a head piece as well. Her body covered. Nuns cover up, Jewish women cover up. A Muslim girl wearing a Hijab or covering her body shouldn't be a "new" or "uncommon" thing in America. All around the world you will see this. And I respect anyone who chooses to be modest and respect their body even living in today's society.

But when they are -blam!-, it's their fault for provoking men with their body?

This makes more sense. Good input.

It has multiple reasons. For one, it shows their surroundings that they are a women of faith. 2: it helps keeping the mind of most men straight. Just like if u would see a woman in some crazy lingerie, you would get sinfull thoughts. The women who dont want to cover their self up can choose not to wear it in almost every country. I think Saudie-Arabie is the only country they are forced to.