I agree, as well. It’s just I wonder at the investment: If you’re thinking pure Sea Zone defense, you’d think 3 SUB would be a better investment than 2 FTR: in an attack, the 3 SUBs would score about 1 hit consistently, same as 2 FTRs. But SUBs can defend in Sea Zones (at least against ships), where FTR’s (without a CV) cannot. SUBs are more survivable than FTRs because they have their submerge/withdraw abilities. SUB hits (unlike FTR hits) cannot be countered. And 3 SUBs represent 1 extra casualty you can take should the battle go poorly.
I guess the reason German SUBs never seem to appear in signifigant numbers is the threat of USSR. It’s easy to justify the money spent on FTRs because when you’re not using them to fight sea battles, you can use them against Russia. SUBs are virtually useless against the mainly landlocked USSR and so nobody ever purchases many of them…what a shame.