Unless they are used to quickly deliver several new-clear missiles to the opponent's coast, clean away the coastline defense, and let the LCAC with marines supported by planes to capture the coastline runways, and receive the cargo planes with paratroopers and the bombers with nukes, to obtain a foothold for the heavy forces on the opposite coast of a straight.
In this case they are simply perfect.
(US just didn't need them, because of large tundra territories or British Islets between the coastline and something, while Alaska and Iceland/Greenland are just asking for them.)