As the old saying goes, kids can be cruel. So can adults. Try to spare the child from negative remarks about his physical appearance, which can lead to larger problems (psychological issues, body image issues, emotional issues, etc.) in the future. Kids (and immature/bitter adults) can always find something to poke fun at. Why not alleviate this obvious physical problem? I am not saying all parents should go out and try to "treat" what they perceive to be physical imperfections with surgery. This is definitely a legitimate issue that can be helped.
I agree with la_angel. This is not a boob job or butt implants. This surgery can definitely help your child feel good/better about himself. I would consider it reconstructive surgery vs. sheer cosmetic surgery. Just be careful about the surgeon you choose.