I don't see how you can say GWX would probably be better since there weren't any AI subs native to SH III either and yet GWX managed to put them in via mods; what's to say that AI Japanese subs couldn't be modded into the game in the same way? Absloutely nothing.
And if they were modded in exactly the same way then they'd be at the same level of GWX, so how would that make GWX better? I'm not knocking GWX, I love it, but saying it's going to be better than SH IV because you'd have to do a workaround exactly as they did it in SH III for SH IV seems a little silly to me. At worst the AI subs would be equal to what's in GWX because they'd be done in exactly the same way.
If AI torpedos were included then even if you only have a surfaced model and a submerged model without being able to change the states, then that'd be even better. Although the numbers being out there bring up another problem, even with torpedos.
For fully functional AI subs I'm just guessing but I think that the problem the Devs would have with that is since the entire ocean is modelled then the AI for subs becomes magnitudes more complex. They have to be able to cruise for thousands of miles, not just in a smallish map like in SH II, they have to respond to enemy DDs and aircraft throughout the entire ocean not just on one map, etc. So basically every single submarine in the ocean has to be able to do all the actions a player does on the same long timeframe during your patrol. So multiply all of those actions, crash dives, torpedo attacks, determining how long each boat can stay underwater, etc. by the number of submarines in the ocean and you can start to see the problem.
Surface ships (and submerged all the time subs which act like simply a submerged surface ship) are much easier to do AI for over that sort of scale in both space and time. They go from point to point, they attack enemy units if they see them and they try to finish their waypoints while staying alive. Their combat AI only has to kick in when they find one sub, yours.
So imagine the CPU load for having 40 convoys or task forces all kicking into combat mode because they detected 40 submarines in say any given hour. Then all 40 of those submarines' AI kicking into combat mode as well but also having to factor in individual dive endurances, crush depth, silent running maneuvering, etc.
That's where I think the problem is. Not that the Devs can't code it, but that it would bring anyone's computer to its knees having to do all of those calculations all over the entire ocean whenever there is any contact between any sub and any surface group. It's just a matter of scale because not only would you have the AI Japanese subs doing all of that, but the AI US ones, and if someone modded in AI Dutch and Brit boats...well that's a hell of a lot of chances for contact between AI subs and AI surface units which means a metric arseloads of calculations that would basically always be running since somewhere in the ocean at any given time there will be multiple such contacts. Adding in torpedo gyro, speed, spread, depth, etc. calculations for every one of those submerged attacks would bring even more load on your system.
At least that's my take on why AI subs are a problem. Not a "it can't be done" thing because obviously it can be, but a problem of the massive scale of the SH III and IV sims in comparison to others where they may be 4-5 subs on a given map, having the whole ocean available means there could be upwards of 150 out there at any given time, all having to do very complex things and sucking up computing power.
All of that is in my opinion, off the top of my head, etc. of course.
__________________
|