Why hasn't Microsoft and OEMs work to improve the usage of tablets as desktops?

Using the Asus Transformer Book T100 as a desktop (via Liliputing)

It really boggles my mind every time I see a video like this and wonder, why it is so complicated, expensive and just inconvenient to convert your tablets into desktop PC's, not only that but also why it this feature has not been marketed properly.

I mean, this stuff is great, if it was just a little easier to use, why are wireless display technologies so under used and poorly marketed, why aren't BT keyboards and mouse easier to pair and use? 90% of the people I know use a desktop setup (latop+kbd+ms+ext display) or a good old desktop PC to do work, and this Atom chips are on par of faster than most of this old desktops.

I know Microsoft is just releasing a docking station with the new Surface, but I'm not really sure a docking station is what the Surface needs..., 100% wireless connectivity, and if Apple has been successful doing screen mirroring on 3 yrs old SoC, why can't Microsoft and PC OEMs already?