Removing the foreskin has real ramifications for not only looks but sexual pleasure (which, by the way, was why it was popularised by puritan Christians in the US – the original point was to stop teenage boys from masturbating by making it less pleasurable).
Cutting off the foreskin at birth takes something from a man that he can’t really restore later, whereas doing nothing gives him the bodily autonomy to make that decision later. You can always remove it if you want, but once it’s gone, you can’t just grow it back.
A baby is at your mercy and has no choice in the matter.