I'm genuinely unsure of how the latter follows from the former. Are you implying that republics lack symbolic representation of governance? If so, then you definitely need to take a look at America. The Constitution is a far more powerful force in America than the Queen is in the United Kingdom, and practical interpretation of the Constitution blossoms from Second Amendment arguments in Alabama and Vermont right on up to the Supreme Court and Congress.
Would you believe, however, that adherence to a constitution like the USA's is superior the retention of a Monarchy?
In principle, I would draw an equivalency between the two, and ascribe to neither principle superiority or inferiority. However, this is solely from a symbolic perspective. In terms of practical governance, the United States draws its authority from the Constitution, and only through that from consent of the governed. The fact that this has turned out well is a testament to the ingenuity of the Founding Fathers in implementation of their ideals, as well as their failures in certain, less noble goals. The United Kingdom does not have a single unitary code of governance in a manner similar to the Constitution, but a far more organic method that has grown from practical customs and precedents over the centuries, along with statutory and common law, developing and evolving with the people it seeks to represent. Attempting to codify it into a single constitution would be, in my opinion, quite stifling to future political development and growth in the United Kingdom. Not every model works for every nation, as Bolivarian nations that attempted to transplant the American model locally in the late 18th and early 19th centuries learned to their chagrin, and as America has yet to learn after its repeated attempts throughout the late 19th and most of the 20th centuries.
Also, all this talk about job preservation: I would argue that the armed forces are not a make-work program or a job agency. Like bureaucracy, their primary goal should never be to make jobs for people, but to protect, defend, and serve the nation. I argue that the existence of a military is not necessary, per se (Costa Rica gets by relying on Big Brother America), but it is not mutually exclusive with the principle of "peacekeeping agencies" - rather, militaries stemmed originally from keeping the peace, and throwing out the principles of the armed forces and replacing them with a new institution will either be pointless (as the old people from the former military carry their principles and goals to the new institution) or destructive (as they throw away such things as military tradition and the concept of an apolitical military). Rather, militaries can and should be reoriented to new peacekeeping roles, especially in an era of asymmetric rather than conventional warfare, but still remain the military.