If BTC is going to become a widely used currency, it needs to be convenient.  Simplest way to do that is by relying on the convenience infrastructure that's already in place.

You'd have a payment form that's already in use at every major store.  People wouldn't have to worry about paper wallets and backups as even if someone stole your BTC from a bank, the bank has ample capital to secure the loss.  Plus, you'd probably get points/rewards just as normal credit/debit owners would.

It's not the "Hooray anarchy lets bring down the world!" idea, but it's the quickest way for BTC to go mainstream.