I've had no problems with nerve endings THANKS. Further, little boys are not the cleanest people in the world so cleanliness is an issue. Finally, no matter how much you clean, there are crevices that trap bacteria. Coitus introduces much more bacteria.
If your culture requires it, and since there seems to be no problem with the culture, least of all, the Jews, I have no problem with it either.
On a very personal level, I disagree with the practice, but that's because I have a right to do so, and it's only the practice I am objecting to.
:^)