Now, now, I didn’t say that it was the mass of 1.0000000 cubic centimeters of water. To one significant figure, “one cubic centimeter of water” is an excellent approximation for the gram.
And I’m still a fan of the meter-ton-second system. That way, none of our base units has a prefix, and we get to keep that the density of water is (to an excellent approximation) 1.