Do you think that anyone born with a cleft palate, cleft lip, hemangiomas, craniosynostosis, facial palsy, or any corrective jaw surgeries should be told to wait until 18 when all of these procedures are far less effective and far more difficult to do?
Fair enough, there are quite a bunch of other cases where it might be justified to accept an imperfect form of consent. Still, it might be argued that some of those are necessary surgeries.