Bad analogy. The metric system isn't easier.
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Actually, it is. It is just difficult for us because we have always used the American/English system, but SI units make a lot more sense when one is converting from one unit to another. For example, figuring out how many millimeters that x meters equals just requires moving of the decimal point -- no paper or electronic calculations needed -- whereas going from inches to feet requires division that many people can't do in their head.
But you do a lot more with a system of units than unit conversions, and everything else is easier in English. And I think many people can, in fact, do whatever conversions they have to do in their head, even in English.
I say this as someone who has been immersed in and completely comfortable with both systems.