I think the biggest problem to simulate is the fog of war and ambiguity of what's going on.
When you're staring at a paper map with a bunch units scattered about, with tangible values assigned to thing, its "easy" to get a solid grasp of the, essentially, static situation and mull on it.
The "Real World" is not so clear.
If you ever wanted to bump your heart rate, try playing one of the old time Air Traffic Control games where you have to juggle the planes flying in your air space in real time. They can get busy, and things can start falling apart. And this was where you had perfect information, and perfect command.
However, one of the most interesting aspects that one game did was that when you sent a command to a plane, they had a chance to a) ignore the command, or b) do it wrong. When that happens, the cognitive load just spikes.
Similarly with these exercises. You have real people, interpreting (perhaps wrongly) real commands, in real time, in a fuzzy information environment, against others who may not necessarily be playing by the rules. Stories of counter forces swapping uniforms and insignia to cause confusion. Perhaps much like the Germans did during the Battle of the Bulge.
Very hard to replicate those conditions on paper (or in a computer).