Lobotomies were popular because they seemed to actually do something unlike practically all medical interventions on the severely mentally ill. They were, as one historian calls them, a "surgical solution" that actually produced measurable results. And though they could definitely do terrible ills, there were many cases as well of them "calming" and stabilizing a patient who was otherwise difficult to deal with, and that often meant at the least that the patient was easier for mental health administrators to deal with, and at best meant they could go home. The question is always "better for whom," and the success of these kinds of treatments were not always "better for the patient" but "better for the people who managed the patient." They were, as one report from 1949 praised them, "used to pacify noisy, assaultive, and uncooperative patients."

The treatment options for institutionalized patients prior to lobotomy were extremely limited. There were some who tried to adapt psychotherapy, but it's hard to use that on the severely mentally ill, or patients who just won't cooperate with the "talking cure." There were others who tried various forms of "occupational therapy" (make patients work), or even "hydrotherapy" (give them lots of baths) — again, the success of these is relatively limited. That's about it, other than restraints, or some more fringe therapies that were used in the early 20th century (such as sterilization or castration as a form of therapy, which was practiced in some institutions). So lobotomy looked like a way out of a cycle of either non-working treatments, or cruel ones (like restraint). Medical administrators and physicians leaped on what for the first time seemed like a genuine opportunity to make progress, something that for the first time looked like a "hard" biological solution to the tricky problems of the mind.

Today we look in horror at lobotomy, and rightly so. It can fundamentally damage someone's mind, permanently. It was far less precise than the doctors knew, and its long-term outcomes could be especially bad. We also know that there are apparently better alternatives: lobotomies declined in popularity once a seemingly better option was available, notably pharmacological medicines. It is worth noting however that even the medical revolution in psychiatry has its many detractors. Many of the earliest and most potent anti-psychotics are also very toxic and debilitating. The long-term benefits of psychoactive medicines are unclear and some argue nonexistent. Despite the apparent promise of being able to finally calm minds with medicines, the rates of mental illness, and the rates of positive outcomes, appear to be virtually unchanged. It may be (many have argued) that eventually we will see these developments the same way we see lobotomies — more promising and seemingly more humane than what came before, but ultimately crude and potentially counterproductive. (I'm not saying that meds are all bad, or can't help people. They can, and so can other forms of therapy, sometimes even surgical ones. But they frequently come with extremely negative consequences as well, and there is increasingly growing evidence that they are not a panacea. Progress in psychiatric medical development has also more or less stalled, and many of the big players have exited the business entirely. See Harrington's book below if you are interested in this; it's fascinating.)

On the history of lobotomies and medication (and many other treatments), see esp. Joel Braslow, Mental Ills and Bodily Cures. On the difficulties with psychiatric pharmacology in general, see Anne Harrington, Mind Fixers: Psychiatry's Troubled Search for the Biology of Mental Illness.

It's important to note that not all lobotomies ended in patients becoming like Rosemary Kennedy. In fact, she didn't have a lobotomy, she had a prefrontal leucotomy and leucotomies fell out of practice once Walter Freeman developed the transorbital lobotomy. Kennedy's outcome was the worst outcome you could end up with short of death and it was more characteristic of a leucotomy than a lobotomy. The majority of individuals didn't have outcomes like hers, so lobotomies weren't seen as being as dangerous as we now know them to be. Moreover, the practice of lobotomy was deeply divisive in the field of psychiatry. Many doctors regarded it as risky and ineffective and it was banned at many psychiatric hospitals, including the home hospital of Walter Freeman.

But more importantly, while modern psychosurgery can effectively treat some psychological disorders, lobotomies didn't "cure" anybody. So were so many performed? The late medical historian Jack Pressman explained it best by saying (I'm paraphrasing here) that lobotomies transformed people into individuals who were physiologically and psychologically different than they had been before and that those changes were then interpreted as being a "true medical benefit". Nobody was cured with a lobotomy. They just became psychologically different people and that that met treatment goals enough to be considered a win, or at least neutral.

The chief personality/psychological difference that was interpreted as a cure was manageability. So you would see reduced aggression, more compliability with nurses/doctors/family instructions, less outwardly extreme behaviors - all the things that challenged families and care providers. It's really hard for us, decades later, to fully appreciate the challenges care providers faced before the development of psychopharmaceuticals. State hospitals were over capacity, psychiatrists were in short supply, and other than the shock therapies (insulin, electrical, and cardiazol), there wasn't much available to "treat" mental illnesses. All doctors and families could do was to be reactionary and just manage symptoms. And lobotomies allowed them to do that better. Even at the time, many doctors knew that lobotomy wasn't a rescue, it was more of a salvage. But in the absence of anything else, salvage appeared (to them) to be better than anything else they could do.

Until psychopharmaceuticals were developed. The entire psychiatric community rapidly jumped ship once an actual rescue was available, a rescue that was not permanent and didn't involve brain damage. Lobotomies had been tapering off anyway as the scientific community made advances in neurophysiology.

First and foremost, an "ideal result" was a patient that could go home. That was the #1 goal for patients undergoing lobotomy - get them functioning well enough to be cared for by loved ones at home. So an ideal patient had reduced aggression, no longer self-injured, and no longer presented a risk for suicide. They showed less outward signs of psychosis and/or mood disruption. Some doctors, like Freeman, were convinced that the patient was cured and went right back to their normal lives. That was unusual. The ideal patient could go home, be cared for by loved ones, and be functional. They could dress and feed themselves, they could help out at home, or sometimes take low-functional jobs. Importantly, the ideal patient still had a personality. They weren't who they were before, but they weren't a zombie; they were still someone. And getting them home helped with the overcrowding seen at most public mental hospitals at the time.

Even if they could never be discharged, the ideal patient was calm and manageable in the mental hospital. They followed directions, no longer showed agitation, and no longer presented a risk to themselves, other patients, and care providers.

So the outcome was never a total cure, and many doctors knew that. The outcome was a change in who they were, and the change made them appear outwardly better and be more easily managed. And this salvage operation was in use because that's really all they had in terms of permanence. Once a non-invasive, non-surgical option became available, lobotomy all but disappeared.