Plastic surgery, being used to enhance or improve a person's natural appearance, is of course superficial. Whether to alleviate feelings of inferiority over breast size or to cover up burns from a fire, the aim is to improve how one looks and make them more attractive or acceptable to society in general. There are often situations where the surgery provides people with benefits beyond the surface, but it is even then still superficial (just not merely superficial).
Although some people may like plastic surgery because they believe it makes them look better or prettier, it still doesn't make it right. Plastic surgery is superficial and fake, even if it gives people confidence. They should be happy and content with what they look like and feel confident about what they look like. If they use plastic surgery to hide their flaws, it isn't what they look like originally and it is superficial and fake.
In some cases, yes, plastic curgery can be simple vanity and show a superficial personality. In many cases, however, it can bring back a sense of worth, can correct an accident, or take away a serious flaw that is noticeable and preventative for employment. Humans are judgemental by nature, and attractive people have certain doors open more easily and wider for them. getting rid facial deformities, bad teeth, or similar disfiguremnts can level a playing field.