Ranged units are currently designed in an ahistorical manner, encouraging players to field forces that are almost entirely ranged. In part, this is due to a number of issues.
1. Ranged units are accurate and typically faster than their melee counterparts, encouraging players to kite with them. This makes players micro their ranged units much like in starcraft. Since 0 A.D. does not wish to have this kind of gameplay, this should be addressed.
2. The proportion of ranged to melee units is historically inaccurate to my understanding. While I think that there should be the possibility of using skirmishing armies, these should have a proper place in the game based on historically informed unit compositions. Here is a general analysis of army compositions during 0 A.D.’s timeframe.
An article from wikipedia argues that Alexander the Great used 31,000 heavy infantry, 9,000 light infantry (ranged), and 7,000 cavalry in the battle of Gaugamela .
The opposing Persian side had only 1,500 archers in an army that numbered between 52,000 and 120,000.
These statistics are not extremely unusual, but they would be in the case of 0 A.D. Here are a few suggestions to address these problems.
1. Ranged units should be much more inaccurate, having the ability to hit targets they did not aim for, making it also possible to have friendly fire. In most cases with at least firearms, it has been common for soldiers to not even aim at a specific target in battle situations. Assuming that this was also the case before gunpowder, the game should attempt to emulate this. Missile trajectories should arc more, and accuracy should dramatically fall off as the distance increases between them and their targets. Highly experienced and champion units could perhaps do better, but these things should at least affect them in part.
2. Most heavy units, especially those with shields, which do a fantastic job of deflecting things like arrows, should be much more resistant to ranged attacks than they currently are. If directional armour is introduced, I think that the idea of them taking more damage from flanking missile attacks would be a nice option, yet for the most part, shields should play a much larger role in calculating defence against ranged attacks.
These are just a few options for addressing what I find to be a problem, and I'd be open to suggestions.