The Imperial measurement system evolved over many centuries, whereas the metric system was devised in France during the French Revolution. Everything in the metric system is based on the unit 10, whereas different imperial measures have different bases. You are probably familiar with the foot, but did you know an inch is based on the width of a thumb? The Romans introduced the mile, as the distance their armies could cover in 1,000 paces (each pace is 2 steps).
In Britain, by law the main system for selling food has to be metric, but other areas of life have been slower to adopt the metric system. Our road system is still in miles, and it is still common to hear people talk about feet and inches, or weight in pounds and stones.
Although you might prefer to work in metric, you still need to know the main conversions, and be able to work between the two systems.