I understand that. However, real battles were also 2-d and not 1-d but it is more difficult to make any change in that regard than we would want.
I know one report of mongolian horse archers would ride in circles near the lines of enemy troops with each archer firing when they were closest to the enemy in the circle, giving them time to prepare another shot as they rode around. Horse archers were notorious for abusing enemy lines while staying highly mobile. They were hard to pursue and did not operate alone, but with the aid of other forces that would then have more freedom of movement as the horse archers distracted the enemy.
The issue would be "no casualties" element. What other unit type can reasonably expect to take no casualties in a large battle. As written every realm would simply make sure to take Horse Archer elements, which would then end up in some running duel with each other.
In RL Horse Archers would come under attack from the enemies archers. Their fast movement made them hard to hit, but then the return fire also caused them issues, as they had to maintain speed to avoid it, which affected their own aim.
Poll