We do but with breakthroughs in science, the future uses are impossible to see now, sometimes they lead to incredible things. When Maxwell confirmed that light is also electromagnetic force with much more than just visible light in it, then all the atom discoveries and after that all the texhnologies like computer and what not, or making laser led to compact disc drives for example. I think precise nuclear measurments might help someday discover/confirm something new in physics

The atomic clocks used in GPS are many orders of magnitude worse than state-of-the-art, and are not a significant limitation for the accuracy of the system.

We seem to have been able to build GPS without this breakthrough.