Though medical tourism itself isn't inherently bad--people who need procedures will find ways to get them, no matter what-- the lack of professional oversight and safety regulations is bad because it can be detrimental to patient's health. Though medical procedures may be inexpensive and easy to obtain in South Korea, a culture that supports extensive elective surgery and body modification will have a negative impact on society.
No, medical tourism is not bad in South Korea, because it allows people who need medical treatment to obtain it. It is a wonderful thing that people who cannot find or obtain medical treatment in one country can obtain it in another. This should be encouraged in all countries, especially in South Korea.