That's a great point worth repeating. Your personal trust relationships probably don't also change when your bank gets hacked and needs to replace their keys,

That's a great point worth repeating. Your personal trust relationships probably don't also change when your bank gets hacked and needs to replace their keys, and a network of a certain size will restore access to your bank relatively quickly due to friend of a friend connections. It also reduces the burden on your bank for maintaining the security of their keys (to some extent). It's still very important, but the consequences are no longer quite so catastrophic.