Quite a lot of the EB timeframe the Romans fielded a militia army. Most of the Greeks who had defeated the Persians two hundred years before EB started had also been not professional soldiers but urban levies. Nevertheless they were able to contain a certain kind of order. But you are right in many aspects, low level units and skirmishers should have a more loose and irregular unit form. In M2TW this is already more the case than in RTW, so I think it will be satisfying in EB II, in the restrictions the game engine sets.