For the sake of this particular theory let us assume that Schopenhauer is correct in his assumptions about music.
Music, according to Schopenhauer, does not elucidate any particular idea in the way the other arts do. Mind you, we are assuming that there is the one-ness of reality, the will, the individualized forms, ideas, and our perception of those ideas.
Music is a manifestation of pure will, that which we are twice removed from experiencing in our daily lives.
I believe that an orgasm orchestrates a similar response in an individual. That is to say an orgasm is an example of experiencing both the sublime and the will. In those lusty throes of passion, we tend to lose ourselves completely in sensation and become a pure knower ( to borrow the term from that esteemed pessimist) of pleasure ( the purest form of pleasure, the idea of pleasure).
So then it should logically follow that an orgasm produced by the nimble touch of a musician, who is capable of manipulating subjectivity through the creation of his art, is especially desirable.
It's as close as anyone can get to physically engaging with the music, which would be the ultimate goal. I'm sure many an artist wishes their creations could manifest themselves as an ideal human being.
The musician then, assumes the role of the idea and the music assumes the role of will.
The sexual union, more specifically, the consequence of said union, results in the sublime.
And so, this is how I explain why people are generally drawn to musicians.
The same can be said for other artists but music touches upon a certain kind of universal vitality and produces a more corporeal sense of emotion. And so the music, and musician, become highly sexualized.
Note: In my mind this theory makes perfect sense. Translating my ideas into an individualized and perceptual work of writing in order to communicate my particular thoughts tends to weaken the validity of my argument.
This is why I'm still in school. To limit the interference of translation with the purity of the idea.