For both this and all of the articles coming out about gravitational wave detection, these technologies allow us to sense things that can't be seen with light. Gravitational waves are produced by binary black hole systems and mergers, which don't give off any detectable radiation, and neutrinos can be produced by spin down of neutron stars we don't have any other easy way of detecting.
But, these also potentially give us a window into the deep past. The cosmic microwave background represents the furthest back in time we can ever see with light, and it happened during the first formation of neutral hydrogen atoms when the universe first cooled enough to allow that, and thus light could travel without being immediately scattered by free electrons, which was 378,000 years after the Big Bang. Seeing anything before that is impossible.
Neutrinos, however, first decoupled from matter 1 second after the Big Bang. The possibility of being able to detect a cosmic neutrino background from this event would allow us to detect the early universe much earlier than we can with light. And if gravity decoupling from the strong and electroweak forces is ever detectable in a cosmic gravitational wave background, that would have happened even earlier, and represents the earliest possible viewing of the universe by any means whatsoever.
I'm not a cosmologist and have no idea what usable data would ever come from being able to see these things, but keep in mind at least one reason we've had so much difficulty developing a grand unified theory and theory of everything even after conquering electroweak, is the inability to produce the enormous energies required to recouple the forces in a lab. A particle accelerator that could do it for strong force recoupling to electroweak would have to be the size of Pluto's orbit. But there is at least one event in nature where the necessary energy existed, which is the early universe. We've just never been able to see it.