4) And even some of the "new" systems, like the GLSDB, aren't really entirely "new". The GLSDB for example just straps SDBs to M26 rocket boosters. The M26 is retired, and turning them into GLSDBs actually saves the US money on their disposal costs.
5) Meanwhile, this war is heavily disarming Russia. The US's military exists to be able to counter its threats. If one of its major threats is disarmed, this allows it to cut future spending to counter no-longer-extant hardware.