Yes that's because effectiveness is exponential, as it ought to be.
I really don't see how anything listed here is a game-breaking problem, especially at an alpha stage. The highest caliber available ought to deliver catastrophic damage, as the shell weight and explosive capacity are exponentially larger with the increase in diameter. Thus, effectiveness is also exponentially better.
With the advent of crew mechanics, campaign shipbuilding limitations and advanced concepts such as barrel wear and build quality, much of these complaints will naturally balance themselves out.