147, I don’t think anybody in his right mind would stand by at a bris and “take pleasure” at the sight of a baby in “excruciating pain”.
First, I don’t think the pain, if excruciating, lasts very long, maybe several seconds, otherwise the baby couldn’t be pacified by any means afterwards. Yes, some babies cry throughout the rest of the ceremony, but there are people out there who are more sensitive and harder to calm down.
Second, and probably the most important, I think the pleasure people take at a bris is knowing that the baby has just become part of the covenant of Avrohom Ovinu. He has received his name and this alone can conjure happy thoughts for the attendees. Why would you think that it is sadistic pleasures that they are deriving?