My mother (well, the first one anyway) died when I was two. I know that how it shaped my life would be different if I were older or younger, but it's not a total rarity for kids to have to deal with parent death.
Most of the people I know who have had a loved one die after a long and painful decline have felt that the idea that we were meant to be "sad but relieved" or even happy that they weren't in pain put pressure on them to behave a certain way during the grieving process. A loss is a loss, and that means that even if death would be better than living for the person, it doesn't always cushion the blow for those around them. Nor should there be an expectation of it doing so.
As for OT, this week has had the very public passing of two women, both of whom died surrounded by family who will love and miss them. Sad, but not any more so than if they died unknown, unloved, childless, single, and unmourned.