I suspect that we simply don't see what the government has available to it already. Even that home-built model has functional military uses already. A coke bottle payload could easily be an explosive device, or a really high resolution camera or listening device.
Or instead of building them bigger and heavier, the military could build them smaller and just build thousands of them. Imagine a swarm of micro-hexacopters, each with a micro camera and small explosive payload (enough to kill a person). Devices like that could sweep through towns and enter buildings. They could run autonomously on large targets and simple navigation missions, but could be run remotely by human operators in tighter conditions or trickier targets.
I suspect this is the direction warfare and surveillance is going.