Lets conduct surgery on a child instead of teaching him to clean properly and to have safe sex. Also because he may, but probably won't, have a medical issue years from now. Just because it has been a tradition and my church tells me I should.
But the fact is that healthcare procedures and such are forced on infants all the time and not just out of religious motives. For example, around a month ago I had to have a surgeon put tubes in my son's ears. He had no choice in the matter but that didn't mean it was immoral for me to have the surgeon do so.