Re: Fix it! Fix it! Fix it!
"went back to being naturally smooth with Windows 8"
WHAT??? Where'd he go... damn, left already. I wanna throw things!
'naturally smooth'. you owe me a LUNCH. Mine just came up!
Seriously though you have identified *THE* problem I think. Prior to Win 3.x (and '9x) 2D FLATTY was the way things like the calculator were done. A 3D skeuomorphic UI is more intuitive, so it was done for '9x at least with the first major re-write [most likely].
And of course the Sinofsky+Larson-Greene "revolution" (2D FLATTY McFLATFACE) forced yet ANOTHER re-write to "that".
But 'calc' doesn't seem to get a whole lotta love, and so it's been relegated to what ended up on github, like some kind of token effort, by engineers who don't even like it nor use it.