Well, when it comes to beastial lechery and untamed lust and such, while men and women tend to like sex within relationships about the same, and men's high sex drive/women's low sex drive is a bit overstated in public discourse, in terms of pursuing exclusively sexual relationships, these tend to be of interest primarily to men, with women usually (but certainly not always) having very little interest in that kind of thing. We can assume in times prior to condoms, the pill, and vasectomies, this discrepancy would have been even more stark. So the question is less "why did this belief change?" so much as "why were they so wrong about this?"

It may be an oversimplification, but it seems pretty intuitive that in societies like the Roman Empire and Europe of the middle ages and early modern period, sexual desire was seen as a bad thing generally, and women were very much marginalized. As is generally the case, marginalized groups get blamed for all of the woes of society. This isn't anything groundbreaking. The number of people I've heard blame overdose deaths Kentucky, where I live, on Latin American immigrants, is astonishing.

P.S. Dracula is my favorite book of all time!! What are you writing about?