I think you're focusing too much on ignoring everything that's been written on this from the original story to Bruce Schneier's commentary.
Every source has reported that the military has been aware of the possibility the video feed might be intercepted by an adversary since operations in Bosnia well over a decade ago. It's basic common sense that the designers must have considered such a possibility as well - after all, they made the control link encrypted.
So far there is no proof that they considered that, if they had they would have probably evaluated the PR fallout from such a breach of security as well.
Judging by how this is playing out in the media so far that does not seem to look too good for those that built this system.
I disagree. Often it's easy for insiders to misjudge public reaction. Insiders have spent a lot of time with a system, they're perception of the system is colored by extensive debates by experts in the system and the consensus results of those debates. But outsiders lack the benefit of that debate and the context of all of the technical details and restrictions the insiders are aware of. To outsiders all of the technical options are equally trivial and outsiders don't have the time, context, or access to people with the expertise to have a serious technical conversation on the subject.
In short, outsiders jump to conclusions based on their, almost certainly wrong, hasty assumptions. Insiders may not appreciate that their extensive technically detailed justifications for their current procedures are utterly useless in the face of ignorant casual public armchair analysis.
Now, whether or not the experts are justified in their position is an entirely different topic, but it's quite easy to see why they may not have anticipated the PR fallout from this problem.
Every source has reported that the military has been aware of the possibility the video feed might be intercepted by an adversary since operations in Bosnia well over a decade ago. It's basic common sense that the designers must have considered such a possibility as well - after all, they made the control link encrypted.