But it's not just in medical dramas. We've seen this in pretty much all of the Hannibal Lecter movies (figuring out the one thing that makes the killer an insane murder machine allows the cops to predict who, when and where he'll strike next) and in every film where the primary villain gets talked out of his psychotic master plan by a hero that "understands" him.
Hell, that's even the ending of Spider-Man 2: Spidey talking Doc Ock out of his murderous insanity. "You're completely right, Spider-Man, I did say that people need to let dreams go sometimes. To Hell with my dead wife and everything else that I've lost, I'm totally pulling this fusion reactor on top of myself to save the lives of all the people I was hell-bent on vaporizing mere seconds ago."
In the medical community, this phenomena is known as "complete and utter whale shit" , but in Hollywood it's call it "the magic key."
"Just stick this in your crazy hole and we'll unlock the sanity!"