The problem you had wasn't just that you were using Imperial
measurements of feet and inches, you were also using fractions like
16ths, 32nds and 64ths of an inch. The metric system doesn't have
fractions. In metric, all fractions become decimals, and decimals are
inherently easier for calculators to crunch.
Just thank your lucky stars that you didn't have to do those
calculations using Roman numerals.
It's amazing that some of the greatest engineering in history was done
using Roman numberals. The buildings, aquaducts, roads, bridges and
weapons of war built by the Romans were all designed and built using
Roman numerals rather that the Arabic numbers we use today.
PS: One of the biggest problems with the Roman numeral system is that
it had no numeral for the number "zero", and that was problematic. If,
for example, a census taker noted that one farmer had no cattle, he
would simply not say anything about cattle owned by that farmer, and
that led to ambiguity. Anyone reading that census wouldn't know for
sure if it meant the farmer had no cattle, or that the census taker
simply forgot to ask that farmer about his cattle. A number for the
concept of "zero" clears up that ambiguity.