Relative to other fields, doctors face an unusually large disincentive to unilaterally change treatments. The preferred defense in a malpractice case is to literally argue that you were doing what everyone else does. You don't have to defend the recommended treatment, just show that what you did was the "standard of care".
I was under the impression that the stories about doctors being conservative and not good scientists date far before, and more universally, than the legal changes which made malpractice suit feasible rather than impossible.
I would guess that, prior to malpractice suits, the main threat to a doctor was a bad reputation, spread by word of mouth among patients. This still provides an incentive to do nothing too weird, but now "weird" means "weird as judged by patients and their loved ones."
Would this have made for more innovation or less? It's not clear to me. On the one hand, patients had less experience in medical matters than doctors, so things that other doctors might have considered normal would have seemed weird to the patients. This might have enc...
Related: Son of Low Hanging Fruit
Another post on finding low hanging fruit from Gregory Cochran's and Henry Harpending's blog West Hunter.