I think Hijab is an islamic concept directed to muslim women, this ad is directed to muslim women, it promotes wearing it, just like antismoking ads promote not smoking.
So I don't know exactly why all non-muslims are so outraged about.
Hijab is an order from GOD to muslim women so this is between women and their GOD.
if you see nuns, they wear veil, if you see the virgin Mary's paintings, she's wearing a veil. Aren't they the symbol of purity in christianity????? So I think this implies that Hijab is a symbol of purity.