I've had an epiphany! I've felt for a long time that many of the men in "Hunks with Small Cocks" aren't really that small; they're what you see every day at the gym. Not big; average.
Today I realized that it's just a matter of perception. Although the average penis is somewhere around 5.1" erect and 3.6" flaccid, porno and modern media depictions have shifted our perception of that upwards. In other words, we now class most cocks which aren't large as small; that is, average is the new small.
We wonder why so many guys today shower in their underwear. In my father's and grandfather's generation, they just looked around the showers, saw how they fit in, no big deal. Now young guys check things out on the internet, feel the pressure, and do the towel dance. Not only guys, but girls. I read the other day that girls check men out on the internet; lots of searches of gay sites (for the male pics) and, interestingly, black sites (checking out the BBC rumors, perhaps). This obviously places more pressure on young men to measure up.
So, yep, I guess most guys post average-sized cocks here because, well, they're not big, which makes them, in their eyes, well, small.