Why no Shutdown option for a regular user? It just has Logout and Cancel.
Linux is a multi-user system and you don't want just anybody shutting down the system do you?
Of course, on a single user implementation it doesn't seem to make sense. But as pi you can
sudo shutdown -h now
sudo shutdown -r now
Or are you talking about in LXDE? In which case all of the above still apply, but you'd have to open an LXterminal window first.
Since a couple of weeks ago, shutdown does reduce the power consumption from about 2 watts at idle to about half a watt.