I do know that most or all of our Navy ships are highly computer controlled/integrated, so maybe the following would be moot today, but...
...wouldn't it be prudent for officers to have the skills to plot and do things on paper in the event that during combat or for other reasons the ship sustains such damage that limits or eliminates the ability to use the computer systems to do that same task?
Again - maybe it's one of those things where if the computer systems are down in such a way that you can't do the task, it is likely that you have bigger problems to worry about. Even so, I would think this would be a critical skill to have, if a "just-in-case, cover-yer-butt" scenario presents itself where it could mean the difference between life or death, survival, rescue, etc.