Android has had HID and games controller support since version 4. Why do so few games work well with it?
Running the tablet through an HDMI lead is pretty awesome. Just a shame that for most games I have to hold the thing like a Wii U controller and make sure I don't wobble the lead loose.
Even a 3rd party hack app that would make various button presses equate to pressing various parts of the screen would be a workable solution for some titles. Give the app the ability to create profiles for different titles, that auto-switch depending on what application ID is running in the foreground.