The simple answer is the US Army opted out of the program early on for what was supposed to be "Cost Issues" and the effect it would have had on the Army's budget for acquiring and/or updating aircraft.
I submit they made entirely the correct decsision and "dollar costs" was not the only cost they saved by that decision.
At least the Army does not put all of its eggs into a single basket....but tailors its aircraft decisions to the mission rather than fitting mission set to the aircraft.
Nothing heard yet about the causes for the Blackhawk to park in the compound. That technique was used at Son Tay....deliberately writing off some aircraft to achieve surprise. I cannot think that was the case here.