Rape is wrong, bottom line. It's massively violating the other person's rights, and whether or not rape is prevalent doesn't matter at all.
Sexual practices have been getting more and more socially acceptable, and that's OK, as long as people's rights aren't being violated. Homosexuality is OK because nobody's rights are violated. Bondage and other violent sex acts are OK, as long as the parties have consented and the "victim" is free to leave when he or she wishes. Anal and oral sex is OK too, no rights violations. The difference with rape is the factor of consent. Nobody consents to rape, and that's why it's wrong. Just because something is prevalent doesn't mean it's ok.
The social roles played by men and women (man= breadwinner, woman= housewife), are a far cry from rape. And just look at what's happened in the last 50 years or so, more and more women are working, more often than not now both parents (assuming they're together) have a job, and the gender roles are beginning to blur. I think there's a certain point that things can get to, but I can't see rape becoming a common or socially acceptable thing in the western world any time soon.