They were installed. They just weren't closed. I guess the captain felt the rooms really needed to breathe... water.
It seems at least most the actual doors were installed, but it also seems they weren't necessarily finished. They were missing gaskets for instance and it seems that some of them may not have been able to close properly. Further many of the compartments hadn't actually been adequately tested for water tightness yet so even some that might have been nominally done could have been compromised. Further still while the doors might have been installed numerous cable, duct, and plumbing runs that pierced bulkheads definitely had not been stuffed and properly sealed and some of these openings didn't even have said pipes and ducts installed yet. The ship's watertight integrity was majorly compromised. A situation made even worse by the facts the dewatering systems hadn't been completed yet either.
So she had at best ineffective doors and many compartments wouldn't have been water tight even with doors due to unsealed penetrations and no testing for defects, and then on top of all that in the event of flooding the only means to try get water off the ship would be portable pumps, which oh by the way the crew had little experience with and didn't really know how to use to best effect! In this condition she would have been in serious danger of loss via progressive flooding in the event of ANY level of underwater damage.
Given the threat of submarines it was incredibly stupid to send out a ship that at that point frankly probably had less resistance to flooding from underwater damage then a fucking cruise liner.
Albacore got Japan's OTHER supposed super-carrier that hilariously went down in one hit.
It was a human factor that doomed Taiho, because you should always, ALWAYS, isolate flammable vapors, not ventilate them and make them go around the ship.
As said before, not only Shinano got torped by one of the best American torpedo from the war, she got 4 of them. If hit by that, Yamato would have been in trouble too, but not only was Shinano hit by 4 torps, but she was hit outside of her torpedo bulge (above it IIRC).
They're pretty eager to ignore how bad that torpedo hit on Yamato actually was. It tore up the armor belt pretty bad, and damage was never really fully repaired, akin to how Warspite's rudder remained an issue for her whole career.
It's also worth comparing the damage Yamato took from a "weak" US torpedo to the damage North Carolina took from a "super" IJN torpedo. The Yamato came off worse, with a gash in her hull much larger than that on the NorCar, and taking on more water.
"A hole 5 metres (16 ft) below the top of her anti-torpedo bulge and measuring some 25 metres (82 ft) across was ripped open in the hull, and a joint between the upper and lower armored belts failed, causing the rear turret's upper magazine to flood.[13] Yamato took on about 3,000 tons of water,[13][24] but reached Truk later that day."
They're pretty eager to ignore how bad that torpedo hit on Yamato actually was. It tore up the armor belt pretty bad, and damage was never really fully repaired, akin to how Warspite's rudder remained an issue for her whole career.
It's also worth comparing the damage Yamato took from a "weak" US torpedo to the damage North Carolina took from a "super" IJN torpedo. The Yamato came off worse, with a gash in her hull much larger than that on the NorCar, and taking on more water.
"A hole 5 metres (16 ft) below the top of her anti-torpedo bulge and measuring some 25 metres (82 ft) across was ripped open in the hull, and a joint between the upper and lower armored belts failed, causing the rear turret's upper magazine to flood.[13] Yamato took on about 3,000 tons of water,[13][24] but reached Truk later that day."
The torpedo in question is actually the Type 95 torpedo, a smaller version of the Type 93 torpedo aka the Long Lance. Still, I have to agree that the Japanese plan of trying to use torpedoes to whittle down the US fleet (this is before the massive buildup) will have failed partially due to the reason you mentioned.
torpedoHow about you?Dec.20 1943TrukYokosukaMust run fastUS submarineI got hit by 1 torpedo but it didn't hurt much...Starboard floodingArmor too thick....Shinano