As you can see in my screenshot, longer instance names are pushing the outer tab buttons out. I’d like to be able to customise the String that appears under my profile icon, or at least turn the labels off for a more consistent spacing.
It's there because many people have accounts on more than one instances. So it becomes quite easy to see which one you're logged in. Very handy button.
I remember Apollo had a similar feature added when a user complained about how a long username would screw with the buttons. It just changed the bottom text to say “Account” when a setting was toggled.