An important point to consider is this:
With doctor assisted suicide, doctors - who are supposed to heal and help - are doubling as executioners. (Of course, there are already the abortionist "doctors"... another evidence of doctors turned executioners.) Suicide, although illegal in many places (I mean, what's the sentencing guidelines for a successful suicide performer?) can be done without any help from a doctor. There are even books about how to do it easily.
What official doctor assisted suicide does is take it out of the realm of private lives and give it the government and medical official stamp of approval. And once it has the official stamp, people WILL BE ENCOURAGED TO DO IT. Of this there is not one iota of doubt. If is okay, or even beneficial, the line of who is "eligible" will change, as it has done and is doing in the Netherlands. And then, there are those too ill or disabled to actually "ask" to die - someone has to decide for them - already happening in the Netherlands.