The yubikey hardware interface is actually pretty clever. Having to press the button means there is physical interaction when using it, which means that if the

The yubikey hardware interface is actually pretty clever. Having to press the button means there is physical interaction when using it, which means that if the auth was successful, the user actually did something. It also means that if it's left plugged in and the machine is compromised, the attacker can't use it. It also means you dont have to worry about drivers, and can use it on whatever OS you want (OK, any OS that supports USB keyboards).