Wow, echo the comments here of how such a basic feature in a mobile device seems to have been omitted.
While the registry edit partially gave a solution so that i can set screen off after x minutes, it still isn't a complete solution.
I use my tablet to set some downloads going then want to be able to push the power button and turn the screen off. I'll then set after how long i want it to sleep of inactivity just in case i forget i have my downloads running. This is exactly how an Android
device works.
'Turn Display Off' clearly works as it's now an option to set on a timer after editing the registry, so how hard is it to have it as an option on 'Power button and lid options' as currently all i still have is Sleep.
I guess another half baked solution would be a cmd line to call the command to 'Turn off display' but I wouldnt know how to do this, maybe someone else would?
Update: This may help some people, i found a program that will turn off your display:
http://www.redmondpie.com/turn-off-your-notebook-lcd-with-one-click/
You'll need to have .Net Framework installed and to run it as Administrator (right click) although if you use UAC you'll get prompted each time so i guess i'm turning UAC off for now. Microsoft clearly need to fix this whole mess, its quite laughable.