Destroyers are honestly way overpriced in comparison to how they were used. They should basically be an anti-sub that attacks and defends on the same as a sub costing the same.
Navy should be like this:
Transport: 0/1/8
Sub: 2/2/8
Destroyer: 2/2/8
Cruiser: 3/3/12, but can bombard. They don’t deserve two hits, as the Hood amply demonstrates.
Aircraft Carrier: 1/2/12, they are cheapened to compensate for the defensive decrease.
Battleship: 4/4/20, two hits, bombard. They are simply too expensive to ever buy. At 20, they are still expensive, but investing in a couple for shore bombardment or hit soaking isn’t such a bad idea anymore. Additionally, this balances them out with the new cruiser, which would become more effective in a bombard but less effective in naval conflicts.
That is, 20 cruisers would kill more land units on average than twelve battleships, but these battleships would kill off the entire cruiser force 83% of the time.
This would accompany a fighter alteration to 3/3/8.
Overall these changes would place less emphasis on defending with a navy, because defending wasn’t necessarily any easier than attacking in naval conflicts.