The one issue with doing it through probate paperwork is that there are a fair number of people who keep their online and RL affairs firewalled from each other - if a person doesn't want their legal heirs to even know their journal exists, requiring it to be part of their RL will wouldn't work for them.

(I do have an internet-executor specified in my will with all of my accounts and where to find the passwords, and I think everybody should, as far as they're willing to link their identities. But not everybody can do that.)