Most people don't write wills. Their assets shouldn't be lost forever as a result. That would be terrible.
It would be better to opt-in to auto-destruct-when-i-die, not opt-out. It's more of a special case. E.g. create encrypted notes for super secret stuff you want to die with you, but let the default security for photos and documents be "private but recoverable in the event of death or forgotten key."
Not to mention, writing that password down in a will would be pretty bad from a security standpoint while you're alive.
