The problem is how we treat mental illness. It's so stigmatized that people feel extreme shame and a sense that they just have to want to be better.
Every single person should be able to walk into a doctor's office, be screened and treated for their illness without the stigma that we attach to it. "Why should I have to pay for it?" This is one, among many, of the reasons. Will it eliminate these incidents? Nope but the result will still be a better society.
(EDIT: listening to CNN in the background, Dr. Drew Pinsky said something along the lines of what we have here.)