Why does the Windows Action Centre need an icon to display in the system tray to say "everything is fine"? That's the opposite of something that requires action and alerts. Were Microsoft worried that people might be unable to find it and might therefore panic, assuming something was so horribly wrong that Windows didn't even know whether anything had exploded?
Mokalus of Borg
PS - Or maybe it was just easier to show it the whole time.
PPS - That's probably what it was. Laziness.