Even as an American Scientist, it still baffles me that we're not metric.
Because the juice of converting isn't worth the squeeze, particularly in the modern era. The benefits of the metric system were minor before you could just google "10 cubic feet to gallons." While there is at least three different definition of gallons, only one is used in the US by average people.
With exception of temperature (haven't gotten quite the feel for the middle of the scale, ie jacket weather vs shorts weather) I can easily work in both systems, and I don't see the benefits of one or the other for everyday life.