Those are very good points crimson (and having met Maniac I echo your comment about her). My sister fosters children and takes them to visit grandparents to maintain the positive family relationships that some of the children have, even those who are going to be adopted. They have memory boxes that are compiled with the support of social services. To think of grandchildren not having that sort of access so they can choose for themselves as they grow seems cruel.
I agree that they don't always know or understand at the time, that a grandparent has suddenly gone out of their lives, and it is more heart-rending for the grandparent in most cases, but children grow up and question why and what has happened. It has taken some months for my grandson to catch up with news about people and events he thinks he has missed as a result of our relatively short separation. My son and I say nothing when grandson asks to repeat activities he enjoyed before the separation, as we can see he wants the security that these things give him. He's nearly 13 but asks if stories can be read to him at bedtime, can he bake cookies and bread like he did when younger, as well as doing things more appropriate to his age such as using the electric mixer or wielding a sharp knife to cut meat. It's easy to forget the impact that separation has on a child, and the secure and constant presence of grandparents is underestimated.