You got me excited there for a second!
From what I can tell, that setting does not affect the UI at all.
This problem only becomes apparent when you start at 1080p and above. The buttons in the menu are displayed at a fixed resolution regardless of the user's screen size. The higher the resolution gets, the smaller the buttons appear in relation to the rest of the screen. At 2560x1600, I have to put my face right up to the monitor to read the text and find the smallest UI elements.
Reducing my resolution so the UI scales up appropriately is not a good solution because LCD screens do not handle image scaling as well as CRTs so everything gets blurry and ugly.
Many modern games provide a method of manually tweaking the size of the UI. See Guild Wars 2 or World of Warcraft.