I am well aware that there are many people whom own laptops as nothing more than 'email/fb/youtube and watching media machines'. I have 7 of them in my family alone (2 parents, 3 brothers, 1 sister and the wife).
But these people already have older laptops which have full versions of WinVista/Win7 on them where are thus compatible with any 3rd party software. One example I can think of immediately is mobile phone-related software from apple, blackberry makers, nokia, samsung etc. for mounting phone sd cards or transferring music to and from phone.
So even they aren't going to want WinRT, which would restrict them to only using Office, IE, and desktop mode for viewing files (presumably played in Windows Media Player), and anything they download/buy from the Windows Store. They also have phones such as the Galaxy S3's or BlackBerrys, so having a touch screen device such as a tablet isn't a necessity.
I simply do not understand whom WinRT is aimed-at.
Even my family whom are mostly casual users, when they come to replace their current laptops, would want the Win8Pro version of the Surface tablet due to it's compatibility with their phone software.