Why modern naval main guns feel stagnant

What is currently the best naval main gun?

None stands out decisively; the larger problem is that navies keep fitting mature familiar systems without rethinking the requirement for today's larger ships.

Current main guns are broadly similar in practical value because all are refined designs with long service histories. The criticism is institutional rather than mechanical: designers know a ship needs a gun, so they fit the familiar option without reopening the requirement. Larger contemporary warships may justify a more ambitious answer than inherited standard calibres.