There are advantages and disadvantages to both the metric system and the English system. The metric system is a logical outgrowth of our counting system. But, as Bert pointed out above, a decimal based measuring system has problems dealing with some commonly used fractions.

That we humans count using the decimal system is a natural result of having ten fingers. If we had twelve fingers, we'd doubtlessly use the duodecimal system for counting. The resulting measuring system would have the logical simplicity of the metric system, but be able to deal with most commonly used fractions as whole numbers.

Therefore, I propose that we begin a program of selective breeding and genetic modification, the goal of which will be to create humans with twelve fingers. Then, in a few hundred years, the problem will simply resolve itself.