Wow, submarines can be FAR FAR more effective in the Pacific than DDs for the simple facts that planes cannot hit them (without a DD present) and more importantly, that sub hits cannot be applied to planes at all (regardless of DD presence). This makes them CV killer in the extreme. If you havent witnessed that, its no surprise you dont advocate a J1 DD build. :)
Also, DDs are vulnerable to enemy CVs which are 3 spaces away. Subs are immune to anything that doesnt have a DD within 2 spaces. This gives them greater freedom to operate.
Keep in the mind the combat sequence. The Defender has to select casualties before rolling their defense. This means that if you have subs present, he might take a higher value casualty to keep a DD alive to prevent first strikes in a following round (or to allow aircraft to hit in later rounds). For example if you have a BB, CA and DD (and a few TRs present) and a bomber and 3 subs attack. If the attacker hits twice, what do you pick? Obviously the BB soaks up 1, but then what? If you pick the DD, then on round 2, any sub hits are going kill without allowing a strike back (meaning potential loss of all the TRs). Rather than risk that, you might lose the CA instead of the DD. As another example, take a CV w/ 2 Fighters, a CA, and a DD. If the enemy attacks with 3-4 subs on round 1 and hits only once, what do you take? Its got to be the CA. What if he hits twice? Again, the CA and the DD, but if you fail to wipe him out with return fire, you are left with a single 2 to defend against a 2 that first strikes. Not a pretty sight for a TF that costs 54 vs one that costs 18 to 24…
Finally, SSs are cheaper hits in naval combat and they attack just as well as DDs (better if there is no DD present because First Strike can be extremely powerful). Subs are EXTREMELY effective combatants if used correctly. And if you dont have proper DDs for support you could lose a LOT of money in CVs/Fighters from lowly 6 ipc units… Either that, or you have to spend a lot of time running and that is a waste of time that is often critical.
Dont get me wrong, DDs are great units too. But they are certainly not ‘better’ than subs in any way, shape, or form in the Pacific. They are different and both have important roles to play.