Even in the Upper class, women are still paid less than men. And more importantly, in the middle, and especially lower, classes, marketers market skanky and low diving clothes, short skirts, and stuff to people that leads to them being oggled at by men, and women. This is socio-economic, and if people saved more money, they would buy nicer clothes.
Victim shaming is unnecessary. Yes, while I agree with the fact that in some cases prevention can be better than treating a full-blown issue, it is definitely not right for somebody to blame his or her actions based on what their victim was wearing at the time. Humans are not wild animals. It should be the duty of whoever the assailant is in the situation to exert self control over his or her actions, not necessarily what they choose to wear.
No, the dressing style of women is not the main reason for increasing crime against them, because there has always been violence against women. Violence against women is one of the major tragedies of any society, but it has unfortunately been a common tragedy throughout the world. It is unfair to blame the way that women dress.