Whether or not an open casket is part of the celebration is an individual family choice. The main reason we have any “viewing” is because it allows people to have a physical presence to focus on when saying their goodbyes. Since most people are visually inclined by nature, it seems to help them see the person, for the death to be “real” to them and allows them to better focus on tidying up the loose ends that they have with this person. A funeral helps people begin to complete their relationship with the person who died, and sometimes seeing the body helps.