In general, I find the US ships are not as potent as the Russian (and not nearly as potent as one would expect from the real life capabilities). I suspect this is a gameplay issue to give the Player some additional challenge.
That being said, IT DOES make sense w/ regard to the missiles you mention as they are SUPERSONIC where the US HARPOON and TOMAHAWK are subsonic and thus presumably easier targets with a greater window of opportunity for CIWS engagement.