I can agree that consent should probably be restricted to those who can actually express it when it comes to assisted dying. I just don't see the same slippery slope in this issue that you seem to, Mr. Schouten.
Using terms like "the sanctity of life" as a pretext by which to demand control over other people's choices is a vastly more dangerous slope to be slipped on, in my opinion. What could be more damaging to the sanctity of my own life than to have someone else making my decisions and demanding a particular set of values from me?
As mentioned in my first letter, those pesky perceptions, limitations and beliefs of ours don't have any say in deciding what other individuals choose to live for or the reason(s) they may choose to die.
Ours is not simply a society where "life is always encouraged," as you say. It is a society wherein the desire to die is systematically demonized and dismissed. As soon as such a desire is expressed, you can expect to be tossed in the psych ward and treated like a child who can't make their own decisions. Those who are not interested in a continued existence have no peaceful and reliable way out. Their only option is to go it alone, with no way of knowing if they're really going to achieve their end, or just risk submerging their unwanted life deeper into misery and despair.
Worst of all, they can't properly say goodbye to loved ones. I don't think anyone's last message from a loved one should ever have to be a tear-stained note filled with grief.
Assisted dying won't be causing anywhere near the amount of suffering that its absence has.