Maybe I'm doing it wrong, but I've always just put the concentrate brick (cylinder?) into a pitcher, filled it up with the right amount of water, and mixed it until fully melted. It's no worse to clean up than anything else in a pitcher would be.
I agree completely about fresh-squeezed juices, by the way. I do my own juices directly when I have time! But the point was about American consumers, who are buying reconstituted concentrate anyways (just that someone's done the reconstituting for them.)