There still is little to no benefit. The Yamato wreck was found 30 years ago and is significantly more accessible (under ~340m under the surface versus >1km)
> It was also a remarkable feat of engineering
Meh. Japan had actually planned for a Super-Yamato class (design A-150), but demand for carriers and cruisers diverted resources and the project was killed after Midway.
> I think there was only one other ship like it.
3-ish, Shinano was initially laid down as a Yamato-class battleship before being remodeled into an aircraft carrier.
And of course they weren't actually useful ships at that point (the US canceled the Montana class without laying a single keel)