I'm still waiting for operating systems to adopt true physical units. You know, that trick PostScript printers have doing since the 80s (running at 300dpi no less). I realize there are large screen projectors in the wild, that's solvable problem. Bitmaps icons are also an issue, but again, solvable.

Real physical units make sense when you're printing on paper.

I don't see how they make sense on screens. A one square inch image is fairly large on my phone, not too big on my desktop monitor, and pretty darn small on my tv. That's not to say that pixels make sense to use for layout at those scales either, but before everybody got into high dpi with scaling, it kind of worked... If you were comfortable with tiny text, you ran a higher resolution and if you needed things big, you ran a lower resolution.