Nicely said. The age issue is certainly a facet of the issue. I have several older contractor friends that carry knives and have to have one that nearly falls open on its own. Arthritic hands and thin broken nails make it almost impossible to open a knife, even an old favorite.
And in the case of my father, they took his pocket knives away from him when we put him in a facility as they were afraid he would cut himself. In his mid 80s, he had never gone a day without a pocket knife. Never. A couple of Christmases ago I went through every knife they had at a sporting goods store to buy him a new one against the advice if his doctor and the wailing and moaning of my sisters and mother.
He was delighted, thrilled, to have a knife again. To his huge embarrassment and disappointment his poor hands couldn't get it open. But he enjoyed carrying it so much he rarely went anywhere without it. When he was sick and couldn't get out of his chair for a few days at a time, he would have my mother open the main blade and set it next to him so he could see it and get to it "if he needed it". Since he couldn't walk and was confined to a wheel chair in the end, "if he needed it" meant opening mail when he was having a good day.
I would have done anything to any knife to allow him to be able to open his own pocket knife. And along those lines, if he wanted to someone to modify any of his old knives to make him happy, I certainly would not have cared what it cost.
I guess we all have different priorities.
Robert