The old alt+f4 in desktop works too (or at least worked in all dev builds I tried. I rebooted a lot so I just used win+d, alt+f4, scroll to the last option and pressed enter.
If we count the number of clicks then there is no difference. In win 7 too user had to do two clicks and only after the first click would you see shutdown button. Same goes for win 8.
1) Escape doesn't bring up the shutdown menu 2) Windows key doesn't 3) Mouse to the left, top or bottom doesn't 4) Mouse to the start menu doesnt
Only to the right will you find the menu. Why a simple button couldn't have been added defies me.