It just so happens that our the liberal outlook on sexuality is nothing new, in fact western views on sexuality and gender roles have undergone a liberalization that started in the middle ages. The truth is that "strange" sexual fetishes and practices are nothing new at all, in fact the oldest set of laws available, Hammurabi's Code from ancient Babylon, has plenty of laws for deviant sexual behavior such as many different forms of bestiality, homosexuality, and incest.
The correlation you are noticing is more accurately connected to the rise of higher populations and information technology. There are more people now, which statistically increases the number of sexually deviant people, and information technology combined with high density urban living has allowed them to communicate with one and other, and has made accessing information about them much easier and more likely through out the course of a persons ever increasing lifespan.
Not to mention a more complex society will give rise to new types of sexual fetishes that are connected with the modern world. Good examples would be things like uniforms (nurse, school, cop)because they are connected to permenant fixtures in daily life that repeat themselves (all cops, nurses, students are seen on a daily basis on tv or in real life).
You couldn't have such a wide variety of sexual deviancy in the good ol' days because there was less available things to develop fetishes before that would impact a person their entire lives. (see how it comes back to technology, dense urban living, and higher populations?). But we do know that they DID have sexual deviancy in all historical ages, however it followed the same patterns that ours do now; people must first have constant contact with these fetish concepts in a non-sexualized nature before they can develop. Which is why the historical era's sexual deviancy relies much on the historical context of the era. For example bestiality and incest in isolaeted large family agrarian villages. As opposed to the growing variety of lingeries used by the olde school rich.
In conclusion; it is incorrect to point the finger at recent liberal trends because western history for the last thousand or more years has been a giant liberalization process that is anything but recent, however the trends of sexuality tend to spike in "deviancy" or more accurately "variety" when logistical factors favor them such with higher populations, information technology, and dense urban living.