I am a man, and I was circumcised at birth. It was done for "hygiene" reasons as a default by the hospital. This was approved of my my parents. I have experienced no observable dysfunction, and am quite happy with the state of my genitals.
None of that makes what happened to me right.
I'm a big fan of the concept of informed consent. The idea that you don't do anything to another person's body without their informed consent is one of the most rock solid ideas in the whole of medical and sexual ethics.
But what to do when a decision has to be made and the person can't give informed consent? Maybe they're in a coma, maybe they're mentally unsound. That's when you have someone designated to make the decision on the behalf of the patient. For children, that decision often ends up in the hands of the parents in these circumstances.
Most of the time, however, the default when the person can't provide informed consent is that you do nothing and wait until they are able. The only time it's ethically justified to act without informed consent is when there is urgency and there is no expectation that the person will become able to provide informed consent until it's too late.
Circumcision has no urgency to it. It can be performed on an adult who can provide informed consent. It can be performed on a child who has demonstrated the full understanding of what he is consenting to. To perform this procedure on an unconsenting infant is thus completely unacceptable, for exactly the same reason it would be completely unacceptable for a parent to consent to have their infant molested.
I don't hate my parents for being misled into thinking this procedure was in my best interests, and I don't hate my body because of the nonconsensual cosmetic surgery that was performed on me as an infant.That doesn't make what happened right, and the fact that it happened to me with so few consequences is no justification for subjecting other children to it.
There's a genuine human impulse to say "I had it rough, so I'm not going to let you have it any easier." This impulse impedes progress and only perpetuates a cycle of injustice. Fortunately there is another genuine human impulse to see to it that our children have it better than we did.