Why plan a 6-inch anti-aircraft cruiser?

Why did the U.S. Navy consider a cruiser with 6-inch anti-aircraft guns?

The larger shell promised greater range, explosive effect, and room for specialized payloads, making it an attractive next step in fleet air defense.

A 6-inch anti-aircraft weapon offered more than a larger caliber label. Its shell could reach farther, carry a much larger explosive charge, and accommodate more sophisticated internal components than a smaller round. The concept therefore represented an effort to attack aircraft at longer range with a more destructive burst, provided the mounting and fire-control system could sustain the role.