Should we move to a single tier rank structure?

Sir, you find aggressive intent where there is none. 

SSG, again, greetings . . .  Roger.  OK, 600-20, I know it well, and your point taken, the chance that a Cadet would ever be in a succession of command situation would indeed be rare, and if such a situation were to arise, perhaps in the case of an SMP Cadet (a simultaneous member who is in ROTC and ARNG and will take a Guard Commission) in a unit mobilized and forward deployed that is then overrun, etc., and the rare and unfortunate situation were to occur, then yes, that Cadet by virtue of position and not paygrade, would succeed in Command.  By a similiar provision of 600-20, a Chaplain Officer would be able to assume Command by virtue of paygrade and not position.  There is a broad world of tradition, history, theory, and practice in how ranks and positions evolved.  I note that you have opined on practice in England, but even there, the practice evolved with wide varience in England, Britain, and UK.  Things on the Continent were even more varied and the actual practice of being a private soldier enlisting into a regiment, or being a young gentlemen and joining a mess as a subaltern, or gaining entry into field rank also varied.  As for antiquity - in Rome the path was generally open to all deserving citizens, and Centruions were routinely promoted from the ranks with the Primus Pilus having opportunity to become a Camp Prefect, generally equivilent to a Tribune, but then, the Tribunes were from senior Equestrian and Senatorial families.  Entry from the Plebiean was possible, from entry-level, and even Plebiean families could enter the Equestrian ranks by showing that they could afford the arms, equipment, and logistical support to sustain same.  Realistically, 'knights' were field commanders and provided all of the equipment for the 'men-at-arms' that accomapnied them - it was then and always has been an expensive endeavor.  As ground Armies became 'professional' in the 19th century, roles evolved, but the basic requirements for entry were the same - the 'officers' gained thier basic education through martial academies and the 'other ranks' joined and became trained on the march.  With technology and secular, post-modern, humanistic philosophies, the idea that 'officers' are an 'elite' contrary to the egalitarian, common good, have found hold in some facets of society - such ideas are inherently detrimental to good order and discipline - in all forces, and especially in volunteer ones, such as ours, there will always be leaders and followers, at all levels - whether the leaders are commissioned or not, they are leaders still, to have otherwise renders to chaos that which is already disordered - the battlefield, where in fact these therories are resolved.  Cheers! 

I was 4 classes away from my BA sir, when the Army announced that it wasn't taking over 10 years of active duty waivers for OCS. I really think they should have gave us trying to get our degree that waiver considering we were trying to go in between deployments.

SSG Maravi is proving my point.