If they want to feel more confident about themselves, and feel like plastic surgery is necessary is the way to fulfill that, then yes, they should. Also, burn victims, abuse victims, etc would definitely need it. Therefore, I think it's beneficial and can look great if used correctly. Go for it!!
While I don't think everyone should be running around having plastic surgery, it can be a necessity for some people. For example, third degree burn victims may need access to plastic surgery in order to move through society without being gawked at and feeling terribly about themselves. Some people are born with deformities that can be repaired using plastic surgery.
As a trans person, I will undergo plastic surgery in just over a year in order to alleviate some of my gender dysphoria.
So yes, I think that plastic surgery services should be available for everyone, so that those who really need it can access it. And if those who don't need it want to spend their own money to alter their bodies for whatever the reason, as long as they are not hurting anyone else I don't really see any problem with it.
People you are beautiful. Don't let people tell you otherwise. I think that if they want to change they are wrong and aren't right for you. So before you go change yourself because you think your ugly just think about it. It could all go wrong. You could become very bad looking and then hate yourself even more.