Again with the "Suicide is Selfish"

It shouldn't surprise me that after the death of Robin Williams by suicide, people are making the same old ignorant comments about "suicide is selfish" and "cowardly."  And maybe I'm not so much surprised.  But I'm angry.  And I'm hurt.

He died of depression.  It's sad.  It's tragic.  But it's not selfish.  It's no more selfish than if he'd died of a heart attack or cancer or a stroke.  And it's no more cowardly.

Mental illness is an illness.  It's not a choice, it's not a character flaw, it's not a moral failing, it's not a weakness, it's not an act of cowardice or selfishness.  It's an illness.  Why is it so hard for people to get that?  Why do people refuse to acknowledge and accept that?