Quite costly to finance two standing militaries( one Federal and a Militia based to keep the other in check). The Swiss do it right, they are also not playing super power (which is now broke), but are neutral but well armed. Of course, they have a geographic advantage with their terrain and location, but also disadvantages. Their small amount of professionals are the core for the militia based system. The citizen in uniform is still the best model to prevent what happened with the US military.