It's a trade-off.

We've thought about adding a screen to a future product, but it begs the question of how much information you want displayed in order to make your authentication decision.

And even if a screen gives you more information, are you authenticating an action where the cryptography terminates in the device? If you are authenticating an SSH session for instance, the screen helps you ensure you are authenticating a login to the right server. Once you have authenticated though, nothing prevents the attacker in your local machine from using the established SSH connection.