Is it important to display a username to a user when logged in?

Our system header currently displays an icon and a username, as seen below:

For reasons of accessibility and clarity of purpose I have re-designed it to display a clearer call to action, as seen below:

I think that the proposed design is much clearer but it did get me wondering: has there been any research done on the value of displaying a username at the top of the page for settings? This is an internal system with single sign on, so a user being on their machine means that they are logged into this system.