While some men like to be on top and feel in charge of the sex act, many prefer having a girl riding their cock. It is much more arousable seeing a girl riding a dick on their own, intentionally impaling her pussy on the hard shaft and stirring to find a sweet spot that will make her cum like a slut. It also gives the men much more freedom than when they are on top because their hands are free while the woman is riding their boner, so they can grope and inspect her body as much as they like.