I've got theories on that. First, I think vampires are usually seen as an old monster. Like, literally. Because they live a long time. And though they don't usually age physically, they'll still be affected by time in terms of how they behave. So, they'll usually be expected to have old world ways. Which can mean more conservative and/or elegant fashion, behavior, etc. The age of a vampire is usally set only a couple hundred years back, with high society and stuff. I think if there were more ancient vampires put to pen, then you might get more hunks. Cause then you're going back to more warrior/hunter societies. Second, in many versions of vampires they don't have to put in effort to be strong. It's usually innate. So~ if you don't gotta work to throw a bus, you don't need to work out at a gym to muscle up. Hell, would the work outs even have an effect? Third, I think vampires are most popular with women, and either a large majority or a loud minority really like more elegant/beautiful, not necessarily strong macho, men. Kpop's popularity is definitely strong anecdotal evidence of that.