[badwolf]

I agree to some extent on what you are saying and yes it's all to do with keeping the sim playable as well as realistic.
In the original game you could make repairs on the run in a few minutes while evading attack, but you can't now with LRT, so the sim is far harder to play with equipment failure and flooding. The strengthening of the hull & slower flooding compensates that and gives you a fighting chance, plus delaying the instant death and giving a more dramatic "Das Boot" effect. The mod "Thomsen's No Instant DeathScreen Mod V1.3" was made because of the instant death and that doesn't have longer repair times.
At the beginning of the war a sub would experience inaccurate and less destructive equipment, depth charging was more to keep them submerged than to destroy, so long depth charge times would be the norm. It would be a lucky hit to take out a sub in one, but if enough accumilated damage was caused it could give the sub problems. As the war progress then damage and accuracy increased until it became a nightmare.
This is what's needed to be represented in the sim, that's why I said having 3 weapons with the same values doesn't look right. Using that model would give a good difficulty curve , so you start the war fighting against damage with a "Das Boot" effect and at the end of the war try to avoid instant death.

You played GWX 2.1 with and without LRT and know the effect. You don't know the effect of having the ASW settings, so test that first before changing anything else.
This is a sim and doesn't fully represent real tactics accurately like the wolfpack, were you could slip in while the escorts are busy elsewhere, so your attacking a convoy without the "herd effect" safety in numbers. This means you make the sim as realistic as possible but with discretion.