Warships whose strategic logic failed

Which Second World War ships or systems most deserve the question, why did we build these?

The Deutschland class and secretive Yamato programme stand out, while some U.S. shortcomings were doctrinal rather than failures of ship design.

The candidates are ships whose existence is harder to justify than designs that simply aged badly. The Deutschland class could satisfy a replacement requirement, but Germany could have used the same opportunity to build a much more efficient warship. Yamato presents a different strategic contradiction: a secret weapon cannot deter an opponent who does not know it exists, because surprise weapons and deterrent weapons serve different purposes. For the United States, several interwar problems came less from individual ships than from operating doctrine, including failures to institutionalize practices such as zigzagging.