The tricky thing is that if no one from family knows you have $$$ in Bank Foo, this money can just lie there unclaimed forever (until taken by the government after N years).
Even if theoretically those institutions should proactively search for deceased owners' heirs in some jurisdictions, I wouldn't trust this to happen.
At least listing all banks, stocks accounts & insurances you have might be really useful. Just set a yearly reminder to self in calendar to send such an email to your closest family member.