Oh, forgot this was about facials! I am not a man, and my man isn't into facials at all. I like them, though we don't practice. I think there's something very primal and total in watching a man cum, and if he's going to do that so we get to watch, might as well be on his partner
I can see why it would be common in porn, where you want "proof" that the guy came and they really "did it". If he cums in her mouth, they need to do these shots where she keeps her mouth open and plays with it. If he cums in her pussy or ass, there has to be a creampie shot in the end. Facials are just easier to shoot, I guess?