This probably makes no sense, but I wonder if another factor may be that there's a certain amount of objectification built into the fannish experience that leads naturally to a shippy/smutty end result.
It's most obvious with something like Sam/Dean, where the actors are so damn hot that you'd have to be stone to not notice, but for me personally, even in fandoms where I don't have any overt sexual attraction to my favorite characters, there's still a certain amount of "want" going on with my reactions. I can't always articulate exactly what it is that I "want" from them (except maybe "more of the same"), but the emotion is definitely there... and it's at least in the same ballpark as sexual desire.
If you look at it that way, with all characters serving as objects of desire in some way, it might actually make some sense that fandom leans toward topics that get the ol' hormones raging.
no subject
It's most obvious with something like Sam/Dean, where the actors are so damn hot that you'd have to be stone to not notice, but for me personally, even in fandoms where I don't have any overt sexual attraction to my favorite characters, there's still a certain amount of "want" going on with my reactions. I can't always articulate exactly what it is that I "want" from them (except maybe "more of the same"), but the emotion is definitely there... and it's at least in the same ballpark as sexual desire.
If you look at it that way, with all characters serving as objects of desire in some way, it might actually make some sense that fandom leans toward topics that get the ol' hormones raging.