The original idea behind imperial units is actually quite nice. They used 12 inches in a foot because you could divide it in so many ways without using decimals. You can take 1/2 of it, 1/3, 1/4, and 1/6 without ever needing decimals.
You can measure 1/2, 1/3, or 1/4 of a meter, why wouldn’t you? Also, seriously, those common fractions aren’t that hard in decimal. Everybody knows that 125 g is 1/8 kg.
That’s not the issue. The issue is that it’s not consistent between imperial units, you have a zoo of different subdivisions between units. You have 12 inches in a foot, three foot in a yard etc pp.
The issue is it gets really unwieldy in multiplication, 1 cubic ft is how many cubic inches… 1728, how convenient.
Tell me how much is 1/6 cubic ft in inches? How many cups are that? There goes your mental math.
(It is also a common misconception that imperial is „duodecimal“. It’s not. It’s counting to 12 in decimal. If you had a proper duodecimal system, „12“ * „12“ would make 100 not 144.)
We all still use 360° in a circle
And you also say 180°, 45°, 720°. Not 1/2, 1/8, 2.