It makes your soldiers competent even at low maintinence - perfect if you have rebel problems but don’t want to pay for full mobilization in peacetime.

It allows operational initiative when your troops stick in battle exactly when you want them to. It makes you fight with close to all your regiments in battle while half the enemy’s regiments have fled. It protects you from annihilation from breaking early.

Morale keeps your troops sticking around when the enemy flees.