I'm uncut thankfully. My parents saw through the misinformation doctors and media always feed us. Probably why I'm not in some nut house drooling over my toes as I chew them off in an offbeat effort to comb my hair.
The only reason I can guess as to why they don't use antiseptic with newborns is because the brain hasn't fully developed at that point and you wouldn't remember the pain to begin with. Do any of you cut people ever remember that kind of agonizing pain from that far ago? I doubt any of us remember before we hit 3. I can remember here and there when I was 3, but nothing before that.
As to the argument of sensitivity, Otis is right in the fact that it would be more pleasurable, but his own argument would work against him as he's never been cut to know how less he'd feel it. Just one of those things that only a guy who got cut later in life would know for sure. But on the other hand, cut guys would feel less so they would last longer. How big or small that margin is as usual, depends on the guy. And we all know guys won't readily admit to a tally if they come up short. So it might make a difference, it might not.