I think it is necessary for people who require it to hide an injury in order for them to lead a normal life. This is the reason for it's development in the first place. If someone is in a horrific accident they can have their face reconstructed to cover up the scars and burns etc.
For someone who has normal features but want's to now change something to look younger I think is wrong. We all want to be the best we can but using a plastic surgeon to change your features for non health related reasons is cheating.
I remember the "cat " woman who had so many operations that it changed how she looked. Plastic surgeons should refuse these individuals the operation, but money talks I suppose.
I think it is a legit choice up to a certain degree. Reconstructive surgery can be a blessing. Breast reduction for women with huge breasts who suffer psychologically and physiologically (chronic back pain for instance) is a good thing. Also some slight corrections if it makes people more happy and confident and helps them to get more life quality as a result.
But there is a red line when people start getting ribs removed, pump up their breasts beyond recognition or get butt injections to please men, repeated extreme surgery with the result that the person looks more like a monster, huge pumped up lips, tiny noses which obstruct proper breathing etc. It should not be easy to get such insane surgery and one should consider to even ban certain things like extreme breast enlargement or butt enlargement because it endangers health.