Yes, and they do. The fact that the leaders of our present kakistocracy don't use it should not be an indictment of the civil and military workers in the US military.
Not when "off the shelf" is the motto. They'd still have to outsource the development and at that point would be questioned why spending that much money when Telemessage sells the product.
Unfortunately, the financial structure doesn't really make it easy for custom DoD software.