In the early days of photography, adults were often photographed in their coffins with members of the family gathered around; it was likely the only photograph ever taken of the deceased.
But that's when people still had a healthy opinion of Death, not the fear that we have today!
This is still frequently done in some cultures. I found it strange, and a bit creepy, when I was a little girl; but, now, as an adult who has experienced the grief of losing loved ones perhaps I have gained a bit of wisdom and compassion. Grief is such a personal thing that, if someone finds comfort in that way, it probably should not be the concern of anyone else. To each his own ... whatever gets you through the sad times ...