The Kingdom of Kush and the ancient Nubian civilization, in general, are important not only for their achievements but also for what these achievements represent in the abstract. The existence of such civilizations challenges many traditional, Eurocentric views of the world and its history. Of course, ancient Egypt is impressive enough on its own, but Nubia is even further south and further away from European influence and, in that sense, more African.
Neighboring Ethiopia and numerous other locales in Africa were home to other civilizations that have seen their share of success too, so Nubia and its Kingdom of Kush are not alone in that sense. Overall, Africa is a fascinating place to study from the standpoint of scholars from all sorts of backgrounds and sciences. After all, Africa is where mankind originates, so its heritage is something that's important for all of humanity to study.