i guess is more easy to just wirte the google password than copy a string, sign an address with the string, an paste back the result in order to tell the system you are the real user,

maybe some standar in HTML5 or a browser extension that allows you to register and login to websites just by pressing a mouseclick and send the string to the hardware wallet, press the hardware button that sign it, and you are logged, registered, or whatever, no need to remember password, no spam, no mails, no option to access the private keys...

how could anyone hack an user account that way? maybe a "man in the middle" virus would work? i mean, the virus shows him the string to sign, he signs it, i get the signed string and i can log in? if thats possible then its not that safe...