We use feet, inches and fractions because we can actually make things to those measurements. We use metric also because we understand math. We also use nautical measurements because we understand that too. As engineers we use metric feet in tenths, hundredths and thousandths. We also don't cry about it. Nothing is simpler than being able to break a full sheet of plywood into even half, even quarters and even thirds. There are also basic natural and God measurements that are importantl with load and weight engineered solutions built into the imperial system. Like flooring, wall studs, and much more. Basically by using the imperial system we don't have to hire a phoney baloney engineer to make things because the error correction, redundancy and long life is built into the measurements, materials and processes.