I agree with Johnny, it’s an act of dominance. I’m not a fan of facials, though, because it interrupts the mood of lovemaking.
Just think: when a guy shoots a woman in the face (and I just got a funny image of Dick Cheney here), even if he doesn’t get it in her eyes or hair or nostrils, everything has to stop while she gets a towel and cleans herself up. What a mood killer.
My preference is to cum on her boobs, tummy, or wherever else she wants. That can be hot as hell, and the mess doesn’t really matter. You can clean each other off later, in the shower.