The thing about surgery is... if I needed it, it doesn't really matter how I felt about it. I'd let them do whatever they wanted if it was necessary. I've had sudden hospital visits in the past and they always do what they can to make it as comfortable and quick as possible.
As for cosmetic surgery, I don't think it ever really needs doing unless there is a reason for it (i.e., somebody needs the treatment from an accident or to alleviate an existing issue) ... if it's purely for cosmetic reasons, let's be honest... it never looks right.