There is a big difference between the government studying a technology and them buying it to deploy. The test of AR for the military may well have been considered a success as it made clear what the problems will be. It would have been a much bigger deal if MS was contracted for an actual weapons system and failed to deliver.

It seems an almost certainty that AR will be applied to the military before any other group. It's basically night vision goggles on steroids, and look how popular those are.

It may have even been a foregone conclusion for the military that the technology was interesting but not ready yet. But you don't know how far off you are unless you try.