My favorite version of this is having a list of beneficiary addresses that can request to have access to the funds; you can cancel the request at any time within some time period. No fancy token required. I built a demo of this a while back: https://github.com/smartcontracts/dead-x-wallet

Yeah, I think the problem with this is that you need some way to store data without anyone being able to read the data on the blockchain.

There must be a middle-ground between your solution (dead simple) and the OP, which I find to be overly complex with all the "Curse", "Archeologist", etc. shenanigans.

Public key cryptography and using the same platform (https://www.arweave.org/) would do.

But where do you store the private key?

The private key is the dead-x-wallet contract.

I wonder what the gas costs are in comparison, contact deployment is reasonable expensive. I wonder if that's why they modeled it this way.

This is exactly what is proposed, the signed transaction is just a transaction as all transactions are signed.