I think you're overrating Iran's ability some. I suspect that Israel / the United States would be willing to deploy even more assets in the face of a significant ballistic missile attack. For example, the U.S. did not even use any if it's AEGIS guided missile cruisers or Arleigh Burke Class destoyers. Both platforms carry a plethora of RIM missiles made for intercepting ballistic missiles. Parking a couple of those off the coast (which I suspect you'll see) would greatly strength Israel's air defense.
*USN ships shot down 3 Iranian BMs in this attack.
*Only SM-3 and SM-6 from standard missiles family is able to shoot down BMs.
People are forgetting in an all out war, Hezbollah (while taking serious casualties) would still launch tens of thousands rockets which would overwhelm the Israeli AD in the region.
And you can't stop someone from launching rockets by air interdiction only.