Thanks for joining the Graphics community.
It seems you are currently having customized drivers from your computer maker. Their drivers will come with certain features as you mentioned the adaptive brightness.
You could try installing generic Intel drivers to try to sort this out.
Please provide your windows version and also if the windows operating system is 32- or 64-bit?
Fully updated Windows 8.1 64-bit.
Didn't seem to work. Although I now have the latest version of the Intel Control Panel (I notice slight interface changes), the Display Power Saving Option is still there, and it still gets Enabled automatically when I unplug the laptop.