I don't think myopia is a good analogy. When it comes to vision, the target is well-defined. Better vision is, well, better. Myopia is unambiguously a defect an

I don't think myopia is a good analogy. When it comes to vision, the target is well-defined. Better vision is, well, better. Myopia is unambiguously a defect and (AFAIK) has no advantages. Curing someone of myopia wouldn't change the person. Neither do glasses, they're an external tool -- not part of the organism. Mental illness is different. A person isn't their eyes but arguably, they are their mind. Treating a personality disorder, in particular, obviously has to change the patient's personality. It is also not necessarily just a defect. Sometimes it's a pattern of behaviors that is perfectly appropriate for certain situations -- but very bad in the current ones. Whereas bad vision is never good.