I support it for people with a definite terminal prognosis, but not for mental illness, where pain has more potential to be managed somehow, and there is a CHANCE for improvement, though the person at the time may be incapable of seeing past their own emotional tunnel vision at the time, so they wouldn't necessarily agree.
People with terminal disease will find a way out if they need to, either way. Might as well help it to be less traumatic in some respects. Having it in a procedural, medical setting, perhaps. Or just knowing that it's ''acceptable,'' in some cases, and helping others to see that, too.