It seems to me that in majority of cases suicide is simply the final symptom of a mental illness that was not or could not be treated and in that the situation

It seems to me that in majority of cases suicide is simply the final symptom of a mental illness that was not or could not be treated and in that the situation is not that different from one in which someone dies for example from cancer. I don't think anyone is really saying that "he should not have committed suicide", what would that even mean really anyway, but it's OK to be sad that we don't always know how to more effectively help people in such cases.