This is a case where the Air Force could have better specified their requirements, but it shouldn’t have surprised Boeing that the USAF wanted the tanker to work with all receiver aircraft. The fact that it doesn’t is more a matter for lawyers to argue than aviators. Looks like the lawyers did, and that’s why the USAF is paying $55M to “fix” it.
What I don’t get is why they did away with the boom operator looking directly out the tail of the airplane. How can natural vision, real 3D stereoscopic vision, be matched by a hi-falutin’ 2D video game? You’re designing performance penalties into the system in too many ways: adding delay, diminishing visual acuity, adding complexity and reducing reliability, and by the way spending more money for the privilege. If, perhaps, they wanted to add some additional visual symbology, etc., they could have still done so with “HUD” symbology overlaying the real world view.