You have this right. Microsoft went to the flat look GUI on Windows 8 because it uses less system resources than the Aero look you get on Windows 7. Now you have enough juice on a desktop or laptop to run Aero with nearly zero problems. But on the smaller devices you mention it is a problem.
So for the sake of a uniform GUI experience across the board (meaning mobile devices/laptops/desktops) Microsoft went for the flat look in Windows 8. Which is also why the start button and old desktop was gotten rid of but that was unnecessary and went too far. A very stupid and stubborn decision. 8.1 still does not have a legitimate start button......
So I install Start8. How much IQ does that take????
Most Windows users are either:
They SHOULDN'T HAVE TO DO IT IN THE FIRST PLACE.
Microsoft screwed the pooch, and their own customers, with Metro.
Even Microsoft has accepted this, and are correcting it. Surely you can do the same. :)