Fugitive, since I quit competitive gaming years ago and I work for a living...I don't go to cons so I woudn't know what HiTech said however many years ago. Regardless of how much of my life I've burned playing this game compared to you (as if it really makes any difference), you seem to be overlooking some very important points.
The introduction of submarines would create a large waterfall of subsequent changes that would have to be created and programmed at the same time. To maintain "balance" (and I hate using that word), for every element that is introduced an opposite balancing element would have to be introduced (i.e. add submarine, add depth charges and/or variable depth torpedoes, more controllable surface ships, additional suface vessels, and sonar). How many different country submarines should be introduced? Let's not forget the subsequent need for controllable destroyers and cruisers equipped with depth charges and torpedoes...how many different country surface vessels should be represented? While we're at it, toss some depth charges on the PT boats...but wait there aren't enough open mounting points on the existing PT boats so one or more gun emplacements would have to be removed or the loadouts in the hangar would have to be changeable. Let's not forget people would want to have external view of the submarine while it's underwater...and what's a submarine without a periscope? So toss in the programming of a functional periscope and 3D external view of the submarine then render the water in such a way that it doesn't kill the frame rates...then reprogram the existing water environment so that it's as 3 dimentional as the above water environment. Can't forget the interior of the sub...that's a lot more complex than any plane. Let's not forget the whines that would occur if the submarine were no more controllable than the current carriers...
Considering the plethora of missing aircraft and ground vehicles that have more impact on this game than ships do...where would you like the limited time and resources of the HTC programming staff to be focused...towable artillery...troop transports...sea warfare vessels...WWI aircraft...or the missing planes and ground vehicles that would benefit the several hundred other people who would prefer new planes and tanks over submarines?