I think it may just be the difference between a Hybrid Shutdown, to prepare for Fast Startup, and a true old-school-turn-everything-off Shutdown.
Windows 8 has a feature called "Fast Startup" (you can see it mentioned in the screenshot which my2cents posted) which is enabled by default.
To make Windows 8 start faster, when you switch Windows 8 off, you aren't really switching it off.
Instead, Windows 8 actually goes into a hibernation state, in which it hibernates some of the internal parts of the system memory by saving them to disk. Then when you switch on, it un-hibernates those parts (which is quicker than booting from scratch) and then loads the rest of the OS. It's not the same as a full Hibernation, as it still loads most of the OS; it's part hibernate, part boot, which is why the term "hybrid" is used below.
I suspect that in this hibernated state, your hardware is still powering up some USB posts, due to the design of your particular hardware.
You may like to test it by trying these two commands and seeing if the hardware behaves differently between the two. (Save your work first, then use WindowsKey-R and paste one of them in, then press enter).
This is a full shutdown.
and this is a Hybrid shutdown, which is the Windows 8 default.
shutdown.exe /s /t 03
My guess is that the 1st will behave like the StartMenuReviver, and the 2nd will behave like the Metro power option.
shutdown.exe /s /hybrid /t 03
If you want to turn Fast Startup off, you can do by unticking that option in the screen which my2cents showed.