Good article, this is important and I've really given it zero thought.
One thing I see in your article is trying to explain things in detail to clients, to get them to 'understand' what I've been doing. Good luck with that. I get so much resistance at that point I've given up trying. Now I only explain whatever I have been asked.
I hear excuses like "that's why I'm paying you," they don't want to have to know anything outside their own work.
I believe they are making a huge mistake, tantamount to not knowing how the backhoe works because they only want to dig holes.
I can see how good documentation would alleviate much if not all worry about a future without me, but I also see where preparing good enough documentation would be a near full time job in itself. Maybe there's a niche for someone, a "technical will" writer.