Understanding the difference between private and public keys is not the whole story. Users need to know about backing these up, but they also need to know how to clear them off of their computer in the first place.

You can go as far as having your private key carved into a metal plate so it'll never get destroyed, but if a copy of it happens to still be sitting on your hard drive, your coins are still at risk. Very few people will know how to securely purge their computer of this critical data.

Even worse, the 'offline' approach in this guide means downloading random javascript from different web services that you are just meant to trust with your private key. It's a disaster.

I was referring to the idea of a "paper wallet". I don't know of many (any?) people who store their Bank PINs on their PCs, so I don't see how anything you mentioned is relevant.

If crypto currency is ever going to replace cash and credit cards, you need to make it easy for 8 year old Timmy and his 80 year old grandma. At the moment neither of them have any concept of what crypto currency is or how to use it, but the sure can go down to the gas station and buy some candy from them with cash.

This doesn't really have anything to do with security, and there's nothing inherent in the way that crypto currencies are designed that would prevent this.

>if you don't mind seeing how much money you have

You can and should create a new keypair for each transaction.

That way you avoid the issue of someone else prying into your expenses.

This is the default behaviour of most wallets