If it works for some grieving people as a method of closure than I am not against the practice. It's not really that much different than the "sleeping" children photographs taken after the death of a child and the mourning jewelry worn in my grandparent's day. That being said I wouldn't want pictures of me taken after death, nor would I take one of anyone I'd lost. That's just not how I want to remember them all quiet and still. It would depress me utterly.
For the same reason, I have no interest in seeing a deceased person in an open coffin. When my father died, my mother asked me to go with her to view his body, and I did so for her sake. When she died (18 months later), I did not want to remember her as a body in a coffin, so I did not view her. It's not that I'm squeamish, it's just that I would rather remember them as they were when alive, not dead.
However, as a professional I can understand other people's feelings and wishes. When a friend asked me to go into the funeral home before the funeral and take photos of her deceased husband in the open casket, I did so, and did my best to make photos for her that she would treasure... just as I would if he had been alive. She was very appreciative of my work.
I have never photographed a deceased child, but would do so if asked.