> It moves it into trusting the protocol design, trusting the implementation of the clients, trusting your local hardware and OS to not be compromised

These are not central parties and they present risks with anything one does with a computer on a network.

> what to do if a transaction goes badly. In the cryptocurrency case, for the most part you're SOL, because cryptocurrencies by design don't allow anyone to e.g. void a transaction.

Transaction finality is a feature not a bug. Whatever conveniences that are enjoyed int traditional banking can be implemented in a layer on top of the base protocol.