The Pacific War COULDN'T have been a bigger catastrophe for Japan even if it was fighting TODAY'S U.S. military, it could just be a faster one.
In this case the biggest difference would be an earlier beginning of the starvation of the Japanese civilian population as American sub attacks become far more effective earlier in the war. Overall, however, the U.S. still has to build the fleet that it had begun in July of 1940 in order to move across the Pacific. That was going to take time so the actual difference in ending the war is negligible.
BTW: The American torpedoes did not all have the same problem. The sub launched Mark 14 weapons had the magnetic exploder problem, issues with its contact exploder as well as the depth holding issues while the Mk 13 aircraft torpedo had a serious fragility issue, a depressing tendency to drop cold (i.e. dead), as well as some issues with the contact exploder. The surface ship launched Mark 15 had some of the contact exploder issues found in the air & sub launched weapon, but were actually a fairly solid weapon, even in early stages of the war that just kept getting better as the war progressed (one of the best examples of this was the Battle off Samar where the weapon was used to terrific effect by Taffy 3's escorts).
The problems and fixes for the Mark 14 are well know so there is no point in rehashing them here. It is interesting, however, to note that later versions of the Mark 14 remained in USN service until the 1970s (when the last of them was finally driven out of service by the excellent Mark 37, which was the standard USN fish of the '60s) while the Mark 15 remained in service until the U.S. stopped equipping surface ships with 21" torpedo armament.
The Mark 13 was the result of a radically different tactical doctrine that that followed by virtually every other navy. It was a slower speed, vastly longer ranged weapon than those in use elsewhere (frex: 33 knots/6,300 yards vs. the 42 knots/2,200 yards of the IJN Type 91) and had to be dropped at very low speed to avoid breaking up. It was effectively the same weapon as had been issues in 1935 despite the incredible changes that the launching aircraft had undergone. These issues were fixed to the point that by 1945 the weapon that would break up if dropped from more than 50 feet and 120 mph was rated to be dropped at up to 410 knots and from 2,400 feet with at least one series of attacks made from 5,000'+ resulting in five of six weapons operating in a nominal manner. By late 1944 the Mark 13 was unquestionable the best air launched torpedo used in WW II, perhaps the best ever used in combat against surface shipping.