Why retain a 16-inch gun caliber

Why give the battleship 16-inch guns instead of much larger weapons?

Sixteen inches offers room for shells and possible missile payloads. Guns of 24 or 36 inches would be extremely heavy and difficult to maneuver aboard ship.

A 16-inch bore is large enough to accommodate payloads beyond conventional shells. Missiles that fit within that bore are one proposed possibility. Suggestions for 24- or 36-inch guns raise a different practical problem from whether the weapons could be fabricated. Such large guns would be extremely heavy and difficult to maneuver aboard ship.