To my way of thinking OTC takes a game with errors in ship lengths and heights, not the same errors they had in real life, but they had many more and more consequential errors than our ship database has.
OTC substitutes the error ridden game database for a database derived by renting each and every Japanese ship on the ocean and taking it to a drydock to subject it to precise measurement and then calls it a "realism" mod. Obviously, the Japanese did not rent us every single ship, military and civilian, for the purpose of letting us obtain precise measurements so we could sink them easier with our submarines. It MIGHT have helped the Japanese to finance the war, though!
In fact, what the Japanese did was disguise cabin profiles and change masthead heights to make our measurements less accurate. They even went so far as to make ships that were scale models of larger ships so they would be misidentified and cause misses.
Study of actual attacks shows that greater than 50% of the time targets were identified incorrectly. It shows that modifications to cabin profiles and masthead heights successfully foiled many, many torpedo shots. And comparison of actual tonnage for submarines and tonnage by SH4 skippers bears out that it is probably on the order of five or six times easier to get a torpedo hit in SH4 than it was in real life.
OTC is for the purpose of making targeting even easier than the one that is already five times easier than it should be! OTC thinks it's reasonable that our identification manual should have no errors. OTC thinks that if you perform your attack perfectly you should have perfect success. Real life didn't work that way.
In its search for perfection, OTC achieves comedy if you're looking for realistic gameplay. In real life you could do everything right and collect plenty of misses. You would never know why you missed either. CapnScurvy finds that unreasonable, and I'm sure the submarine captains of the time thought so also, but it was what it was: reality.
However, for training, OTC is useful. Why? Because it ensures that if you do your job right your target will go boom. If, when you're learning, you get misses, but don't know if the game's targeting mechanism is at fault or your technique, you have a two variable problem. There is no single solution to a two variable problem, so simplifying the situation to where all errors have to be yours makes sense there. That's the only scenario where I would advocate temporary use of OTC.
Now if OTC separated correcting the optics from playing games with the ginned up identification manual I'd be all over it and the optical correction part would be highly recommended for gameplay use.