I'm back to my question. If it's not medically necessary, and this means it shouldn't be done, why do doctors do it? Are they violating their "first, do no harm" dictum?
Doctors do it because it's customary in American culture. This was initially an outgrowth of Jewish influence on American, and in particular American medical culture. The only reason circumcision exists is because of a religious mandate; specifically Jewish (and to a lesser extent Christian), and Muslim. Muslim influence has been notably missing from US history; so it can be said that it is predominantly Jewish influence that has developed into custom; with the assistance of the fundamentalist Christian community.
This would have been insignificant in the long term, outside a small religious community; except for certain religious fanatics who held profound influence in culture and government, who promoted infant circumcision as a way to prevent masturbation. Their support was typically backed up with a great deal of pseudo-scientific medical woo, and religious moralizing.
Even this would not have been sufficient in the long term; but then the US military got into the act, insisting on soldiers being circumcised in order to prevent the spread of venereal disease; again based on pseudo-scientific woo, and profoundly counter-productive.
Infant circumcision did not become commonplace in the US until the 1950s, so it's not even as if it has a significant history in US culture. It's a very new phenomenon, easily within the lifetime of many people reading this board. There are no historical justifications for it, just as there are no medical justifications for it.
Infant circumcision is enforcing a religious and pseudo-scientific precept that is not even necessarily part of the religion of most people adhere to; and does not even have a historical cultural basis to fall back on. Attempts to justify it as medical necessity, or even medical irrelevancy, have consistently fallen flat, due to the complete lack of evidence of necessity, and the wealth of evidence of harm.
Are they violating their "first, do no harm" dictum?
Yes, but doing so for cultural, religious, or ideological reasons is nothing new. Any number of problematic actions have been undertaken by the medical community in violation of said dictum. Forcible sterilization of the developmentally disabled jumps immediately to mind.
My answer to those rhetorical questions is that it is medically neither here nor there,
Wrong. There are no valid reasons to do it, and quite a few reasons not to.
but a cultural practice of no real import outside of the couple having it done.
Wrong. There are a number of complications that can result from circumcision, even if performed by a medical professional. Add to that, it's a medically unnecessary cosmetic procedure that is done without the patient's consent. This is not a good precedent to set.
The doctor does it because there's no real reason not to, and if it is going to be done, it ought to be done competently.
Again, wrong. Doctors do it because of public demand. See previous comment about complications. It should not be done, period, except by adults choosing to do so for themselves.