True, but then you got some unrealistic behaviour like militias holding against elites for quite long plus morale doesn't prevent the killing from happening faster... It justs stops units from routing so fast.
Imho the best way to make battles longer without any need to mess with hitpoints (which require futher balancing if they get tweaked) is just reducing lethality. Works wonders and it's side-effects are minimal, even in worst case scenarios.