I never would. My nose was HUGE growing up...then my face caught up by around college and it's quite proportional now. Had my parents gone and allowed me to go under the knife at a young age, who knows what I would look like today.
Our kids have our combined genetics, My daughter has my mother's side's mouth, my nose shape, my husband's big brown eyes and my son has my husband's grandfather's awesome ears--if genetics hold true, they'll be quite large when he's an old man, but when my boy was a toddler they kind of pointed out a little bit at the top and he totally looked like an elf!
I can just see it, a kid gets plastic surgery and ends up having their own family "Oh honey, he's got your nose!"...with a response of "Oh, this nose isn't my original one"..."Then whose nose is that?!"