I think currently most of these things are dominated by other sources of noise such that a more precise clock isn't that big of an improvement, but the article

I think currently most of these things are dominated by other sources of noise such that a more precise clock isn't that big of an improvement, but the article claims these kinds of clocks could also be smaller than an atomic one, which may make them worth using. Could be useful for things like submarine navigation via gravitational mapping or other applications where size and lifetime/maintenance requirements might favor this design over a standard atomic clock.