The Alaska's were just about right. USN Intelligence falsely believed the Japanese were building a Super Cruiser that would outclass the new Baltimore Class CA's. A ship that outclassed a Baltimore, say a 20,000 ton ship, with 10" guns could only be countered directly by something about the size of the Alaska's. It's like the case of Jacky Fisher creating the Battlecruiser to kill Armored Cruisers. In this case there were no Japanese Super Cruisers, and the Japanese Cruiser Fleet was dealt with by their counterparts, and by Naval Air Power. The Alaska's were left to serve as AAA platforms, and shore bombardment.