It is generally accepted that weres and vamps represented various aspects of human sexuality to repressed Victorian England. These aspects were feared, as such, weres and vamps were scary.
Fast forward a few hundred years to the present. I believe there is a reason women are the ones who have most changed weres and vamps. These same aspects which were feared and repressed are now accepted and even openly celebrated. As women's relationship with sexuality changed, so did the creatures which represent it. I do not believe this evolution was entirely conscious. Symbols work best when they speak to or for our unconscious.
Many writers of urban fantasy and paranormal romance have weres and vamps as integrated parts of society. Few have them as necessarily evil, or if the race is inherently evil, there are those struggling not to be or are motivated by the heroine to be good. This parallels our feelings about sexuality.
There was a recent article about how the popularity of vamps can be explained because women want to have sex with gay men. The writer missed the point. There are many reasons weres and vamps are popular now. If there weren't, they wouldn't be so popular. It takes many individual reasons to make a phenomenon. I would put having sex with gay men very far down the list. Near the top is modern weres and vamps are a statement of female sexual liberation. They are a way for us to externalize the rapid changes going on within us. By externalizing it, we can better understand it.
Which to me is the highest goal of writing--to help us understand something, hopefully ourselves. You will see me write about this topic often. Even escapist literature, or most likely especially escapist literature, bypasses conscious thought and can speak to the unconscious. This happens both to the writer and the reader. Weres and vamps are two popular vehicles for this currently.