Should they dress 'modestly.'Simple answer, yes.
The reality of the situation is what it is, should they have to, no.. It's simply safer for women to dress 'modestly' and preferably go with male chaperons in many parts of Europe now, can you imagine what this summer is going to be like for young German girls and women when they attempt to strip down into bikinis or hot pants.......... yeah, they should wear burkas or they will be assaulted by Muslims.