It's nice to be able to fling the mouse up and right, not having to bother with precise targeting, and click. If your hand's already on the mouse, this is easier than switching back to the keyboard to press Alt+F4 for a quick window close.
E.g. Windows (since at least 95) has made this work, although they at times had very annoying almost maximized window defaults that interfered with this quite a bit in some applications. Nonetheless, actual maximized windows have always capitalized on Fitz' Law in their design this way.
Is there any way to get this behaviour in Linux Mint MATE 18.1? (Marco is the window manager, it seems.) As it is, maximized windows will not close with a click in the upper-right corner. One has to precisely back up a few pixels to activate the X and close it.