Primarily, It’s a sub-conscious safe play. (I’ve looked this up with a PHD psychologist FWB). Psychologically the lips of the mouth represent the pussy lips, which is why women want lipstick and lip filler to suggest their ‘lips’ are aroused in order to appear attractive. Men in turn like to cum on a girls face because of the proximity to the lips, but keep the safety of not getting the girl pregnant. They see the cum and they see the lips and become psychologically satisfied, The domination element comes from the fact that the girl has to agree (or submit) to doing it so for guys that like that dynamic it lets them feel in control whereas, and for the guys that like a connection with the girl (GFE feels) having the girl take a facial is like she’s pleasing her partner and reinforcing the relationship. Guys that like girls who take it with a smile would likely be the guys that like DFK and GFE.