...think of what is required on the battlefield for a combat soldier, Aikido is the wrong MA, for the task at hand
Your right, Aikido, is probably the wrong MA for a battlefield, since O-sensei evolved it to be an art of love not of war, but the precursor of Aikido is Daito Ryu Aikijutsu and that MA
is indeed developed on the battlefield for the battlefield, and remember, the men in Japan 400 years ago were far more often, than modern armies, fighting close quarters. So D.R aikijutju workes, and that's why the techniqes you see e.i in US-army are similar to them, I mean they all want thiere troops to have the best chance of surviving and win a man to man encounter.
On the other hand, to use e.i D.R aikijutsu in the battlefield takes several years of practice, since you have to integrate the techniqes as second nature in your body and that includes the Aiki-techniqes (the ones O-sensei evolved to Aikido). And soldiers today don't have enough time to learn the hole system, only as you say the core of it, and then they might loose parts that actually makes the rest work. As Bruce Klickstein wrote - If you cut a coin into half it will no longer be worth half of the original coins value, and the same goes for Aiki in Aikijutju(do). (Or something like that!)
Anyway I hope that made sense.