Here's where I think it gets interesting:
In the books, Sookie (the female protagonist), occasionally fantasizes about Eric (vampire) despite being involved with Bill (other vampire) because...well mainly because she seems to be a warm blooded woman who's willing to spare a thought or two towards any guy with his shirt off.
On the TV show, she fantasizes about him as a magical side effect of having had some of his blood, which he tricked her into.
In the books, Sookie ultimately finds Eric attractive because of his sense of humor and impressive anatomy.
On TV, impressive anatomy may or may not figure into it...but Sookie's primary interest in Eric stems from finding out about his inner torment.
I think it's fair to assume that the producers of the TV show wanted to appeal to a wider audience than the books. I think it's likely that their goal was to move from a mostly female audience to one that included at least a strong minority of men...maybe not men who would then go and list the show as one of their favorites on Facebook, but ones who wouldn't complain when that's what their wife wanted to watch on Sunday nights. And so I think it's interesting that these are the changes they came up with; a female protagonist who is more loyal (at least mentally) and whose turn-ons include angst and brooding. Also interesting; as a woman, I find these changes pretty disappointing.