I answer this question in part here: https://www.reddit.com/r/AskHistorians/comments/53d3a7/how_have_admissions_standards_to_medical_school/d7sjrr3.

I would say that it depends on the region you're referring to, but in the United States, the consolidation of professionals under the AMA heavily bolstered the status of the profession. Also, once there was a system of licensure in place, not everyone could be a practicing medical professional, lending physicians a more exclusive social status. Also, see Brown 1979 (Rockefeller Medicine Men) which argues that physicians' professional alignment with the sciences through the 19th-20th centuries increased the legitimacy of the profession, and also caught the interest of wealthy industrialists, who saw 'modern medicine' as a way to improve the health and thus productivity of workers.

The advent of modern anesthesia and cleanliness practices also rendered surgery (typically seen as rather brutish) much more humane, and the ability of surgeons to perform more radical, life-saving interventions without causing the patient further harm made them highly valued professionals.

I would recommend Roy Porter's history of medicine if you are interested in these issues: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=The+Greatest+Benefit+to+Mankind&stick=H4sIAAAAAAAAAONgFuLUz9U3MKqwzLFQ4gIxzczyKpPLtAQcS0sy8otC8p3y87P983IqAUtB1GsrAAAA.