After all, pornography works in the most basic of ways on the brain: It is Pavlovian. An orgasm is one of the biggest reinforcers imaginable. If you associate orgasm with your wife, a kiss, a scent, a body, that is what, over time, will turn you on; if you open your focus to an endless stream of ever-more-transgressive images of cybersex slaves, that is what it will take to turn you on. The ubiquity of sexual images does not free eros but dilutes it.
Other cultures know this. I am not advocating a return to the days of hiding female sexuality, but I am noting that the power and charge of sex are maintained when there is some sacredness to it, when it is not on tap all the time.