It makes us unique. Besides, in Physics, i find everything in Newton/Meters, grams, centimeters, celcius, etc. We don't (most of the time) do major scientific stuff with imperial, and they teach us how to convert between the two, so i don't see how you can say that all of our measurements for physics are in imperial. But, why should we change our regular life? We all know of everything in gallons, pounds, miles, etc. Just like all y'all know of everything in liters, grams (actually, grams is a measurement of mass, not weight. bet ya didn't know that), kilometers, etc...