The reality is that it makes signing in slower and painful.
The idea is that Google stores the user name of a particular account so that the next time you sign in, you can sign in faster. Great idea.
Except that most us folks at home would have a machine that is used by a minimum of 2 people - and sometimes they have multiple accounts. And there is no way we would want to stay signed on a machine with multiple users...
So, if Google, did not, helpfully, remember the name - all I would have to do is enter the username and the password. Now, thanks to google, it chooses to remember one id - because of which I have to navigate 2 other pages before I get around to entering the user name and password.