Wartime submarine refits as a bridge to nuclear boats

Was refitting and modernising the Second World War submarines the right decision?

Yes, because they provided useful boats during the lengthy transition to nuclear submarines.

Modernising wartime submarines gave the fleet usable boats during the transition to nuclear propulsion. Nuclear replacements took a long time to arrive. Refits extended existing boats' useful service through that interval. This continuing need for submarines makes the modernization decision worthwhile in the assessment here.