Interestingly, the problem the existing weapons had is that they had terrible engagement characteristics for things that were close and fast at sea level. CIWS wasn’t built for that. It wasn’t in the original threat model. They were designed for low planes and cruise missiles.

The boat swarms would close the distance fast, and the US Navy was reluctant to engage potentially stupid but non-hostile targets. By the time the threat was clear the defensive weapon systems were outside their design parameters. The alternative was killing everyone a long way out even if they weren’t a clear threat.

Not an issue today, they have loads of weapons purpose-engineered for that threat. But they had to learn that lesson the hard way.