To give some perspective on why this is the case from an American, it isn't that a bunch of parents are asking / going out of their way to get this done, it's that the doctors almost always offer it with the justification that it's a preventative measure against infections, and the parents generally don't question it due to how commonplace it is already. The cultural reasons that started this haven't been popular for decades and it's only the medical establishment that's keeping this going.