I would like to see a change to siege in this game that requires a minimum number of heavy (I.E. Legion, Iberian, heavy infantry, etc.) units be required to siege a city based on its population size. It’s a tad unrealistic to see a tiny auxiliary unit of perhaps 900-1200 total men march up to a large city and set siege to it and cut off all supply.
In game terms the net effect is that any garrison units are then required to sortie outside their works to drive off the tiny unit else they will die/surrender. If the garrison is heavily dug in, they lose their entrenchments due to the sortie and that allows a larger force to come in and easily take the city by storm. Not to mention the fact they are forced to remain outside the city for a full month thus risking another stack coming along later in the turn and crushing them.
If each heavy unit was capable besieging 3 or less population, then a large city like Athens with a size of 11 or 12 would need at least 4 heavy units to set siege to the place. Anything less and the city would still be allowed to create supply. Or perhaps only a percentage of its total supply production ability.
Anything is better than allowing tiny units to starve out entire cities. Even a simpler solution that saw only heavy units allowed to set siege without any other limits would be preferable.