I honestly think everyone should have the right to do whatever they want to their bodies. It's goofy, and they may look stupid in the process (Michael Jackson is a perfect example - the poor guy looked like an alien by the end), and it seems as though it is addictive.
I do think it's important that one approaches it with a sound mind. In medical cases, reconstructive and cosmetic surgery can make a patient feel whole again.
If someone is doing it for purely cosmetic reasons, do they fully understand the consequences? Currently, the country of France is paying to remove defective breast implants. Are they being encouraged by their partner? Or, do they feel they need it for professional reasons? If, for any reason, they are being manipulated into getting surgery, then it's a bad idea.
Also, their personal motivation should be examined. If it comes from a sense of low self-esteem, then cosmetic surgery isn't going to make them feel better.