There are people whose brain chemistry is so screwed up that no amount of treatment is going to fix their depression. Treatment-resistant severe depression is a big issue. Is it society's role to prevent that person from doing what they want to do to when that thing would also avoid the constant pain that they're currently undergoing? Why isn't it up to that person to make the choice to end their own suffering? I'm not proposing this as the best path for all or even 98% of cases...but I'd claim for those 2%, it's akin to torture to force those people to stay alive when they don't want to consistently and for a long period of time.
On top of which, we now live in a society where insulting, ridiculing, and just generally harassing or terrorizing anyone "different" (but especially those with depression or other "mental issues") is the normal behavior of most humans, making any attempts to live a "normal" life pretty much an impossible to tolerate waking nightmare hell-scape for many who suffer with "major depressive disorder" (or whatever it's being called this week.)
