I think what this game needs is a cavalry population. You need people for infantry, so why not make cavalry require men and horses.

This would make a great improvement to the game IMO

First no 15 units of macedonian cavalry. Italy could have low population of cavalry to represent Romes weakness in there numbers while the eastern territories have a high cvalry population with a high production rate.

Alls thats needed is a base reproduction rate for cavalry and should vary upon region along with stables increasing cavlary reproduction rate just like farms increase population.