A little background info is in order. Congress mandated over a decade ago that USN find a replacement for the retired battleships which provided naval gunfire support (NGFS). DD-21 was USN's answer to that mandate and DD-1000 takes over that mandate after DD-21 was cancelled. The BAE Systems advanced gun system of the DD-1000 obviously cannot completely replace the 16 inch guns of the retired battleships, but they are capable of providing "impressive" gun fire support. And not all the artillery ammo is expensive. Sure, the guided projectiles are pricey, but dumb projectiles are also available which are much cheaper.
As for missiles, DD-1000 has extensive missile capability. She's outfitted with 80 Mark 57 Vertical Launch System (VLS) cells, which are considerably larger than the usual Mark 41 VLS cells. That means she can carry and fire any land-attack or anti-ship missile in the USN inventory. And 80 such missiles is a lot of missiles.
Her armaments/magazine design is also unique to enhance survivability. Rather than a concentrated magazine that if penetrated and explodes will tear the entire ship to pieces, DD-1000 has a distributed magazine system with armor on the inside of the magazine rather than outside. The idea is that if the magazine takes a hit, it will explode outward and leave a large hole, but the ship's structure and systems will remain (largely) intact. And with multiple widely distributed magazines she will not only survive, but be able to continue the fight. That's the idea anyway. Only time and an actual engagement will prove if the idea works or not.