The human eye is attracted- mostly by shiny objects and moving objects. So when you are presented with porn video where a majority of the motions are a woman furiously rubbing her clit over a guys head while he frustratingly jerks off- it's a torturous ballet as you reluctantly keep eying these two actions.
To avoid the guy completely is impossible: his mug has to be featured as it's the target of the piss, and often, the framing is in such a way that you have to see his entire frame.
That aside, the porn itself is basically for the individuals that wanted to picture themselves in the part of the whore recipient of piss in Lesbian Bukkake 10. One thing I really wish I didn't have to see was the guy that was shadow boxing in the nude, as well as the couple of times the camera would close in to get a reaction of the guys face and his face trickles with piss.