For all the sins of past societies, they at least had the good grace and civility to regard those who spoke ill of the recently dead (even if deserved) with scorn. There are times where, as F. Scott Fitzgerald once wrote, "To be kind is more important than to be right."
Let's celebrate the good parts and forgive the bad parts of a person's life at it's end, just as we would want others to do for us. Leave chewing over their failings to those pale few who derive nourishment from it.