It's the nature of depression that he might have even thought he was doing his family a favour.
Suicide is often a reaction to a set of constraints that are perceived to be unsolvable. I.e. I can't fail, but I'm gonna. I can't let my loved ones down. I can't stand to face my friends after doing X. The pain is unbearable, so I'll just save everyone the trouble...
Imagine a warrior who commits suicide rather than admitting defeat, because he can't face the shame (quite possibly imagined) of failing in his duties.
In all of your examples, you are depicting suicide as a short-sighted or cowardly act.
An alternative explanation is that suicide is often committed in the pursuit of pain relief. It may be seeking relief from a terrible situation, a chronic illness, cultural damnation, or any other source of suffering.
If your example of a warrior committing suicide was meant to refer to seppuku then the warrior would not kill themselves "because he can't face the shame". I suggest you learn more about the ritual here: http://en.wikipedia.org/wiki/Seppuku
I don't think that it is right for one person to judge the level of suffering another is willing to endure.
Suicide is often a reaction to a set of constraints that are perceived to be unsolvable. I.e. I can't fail, but I'm gonna. I can't let my loved ones down. I can't stand to face my friends after doing X. The pain is unbearable, so I'll just save everyone the trouble...
Imagine a warrior who commits suicide rather than admitting defeat, because he can't face the shame (quite possibly imagined) of failing in his duties.