Because through mankind the celebration of transition (birth, adulthood, marriage,death etc) is helpeful both for the individual and society. The individual benefits from announcing they are now taking on a new role. Obviously less so with death, but all transitions help the immediate society transition as their roles may change so although you may not benefit, it will help those close to you.
However, your life, your rules. But by the same token, you’ll have little control over what they do when you’re dead.