I have a ton of very sensitive client data which I store encrypted and secure, there is a protocol in place such that should I pass away or retire their information will be securely erased. It may not matter to me once I'm gone but I feel that as a decent human being I owe it to those who place their trust in me to honour that trust to the fullest extent I can. I would say the same about my family, I wouldn't want them torturing themselves by combing through my files (assuming they could access them) and looking for clues and misinterpreting things, I would rather know that I have left them without such worries after I pass.
It's a personal preference, but just as I have a written will, basic funeral arrangements and other wishes recorded, I feel more secure in knowing that the 'admin' of my death would be taken care of before I left. One less burden to leave for my family and friends.