Okay, so what is the Total War vibe, then? Why does Total War use battalions? Why not just have hundreds or thousands of little dudes running around individually? It's because battalions give the opportunity for greater control for the player, including directional attacks, flanking, charging bonuses, fatigue*, morale*, formation bonuses (and weaknesses)... all of the things that make ancient warfare interesting.
You can have the benefit of 1000 soldiers vs. 1000 soldiers battles, but with easier player control and combat dynamics. You'd have a couple dozen entities (battalions) to manage in that example instead of 1000. For all those people who desperately want an 'ammo' feature*, battalions make it easier to do.
And it would be less like Total War and more like Battle for Middle Earth 2:
*Fatigue, Morale, Ammo aren't 100% necessary, just easier to implement and manage if desired.