Why Italy rebored battleship guns when others did not

Why did Italy increase the caliber of existing battleship guns while other navies generally did not?

Italy had more incentive to replace weak gun performance, while Britain could improve its already effective 15-inch/42 system without reboring it.

Italy had stronger reasons to alter unsatisfactory existing weapons, whereas Britain already possessed a successful 15-inch/42 system. A caliber increase was therefore worth the disruption for the Italians but offered less return to the Royal Navy. British modernization concentrated on mountings, mechanisms, propellant, and improved shells. A new 15-inch/50 family might have justified a larger change, but the existing gun remained effective enough to retain.