Oh? Be specific. In what ways? The only real advantage a mortar would have would be range, especially in AH.
Ability to fire High Angle from reverse slope..
In general, a mortar shell will have a higher capacity of HE filler than an equal caliber of Arty shell, because the casing of the projectile can be made thinner.. Yielding a larger blast radius and more destructive power against soft targets like buildings and Hangars..
Can't find the weight of the HE fill in the 75 or the 81 tho..
Can't go by total weight, because of the thicker iron casing of the HE Arty shell makes them heavier every time..
Iron is heavier than TNT filler ya know, lol.. So i can't make an exact comparison..
A mortar has no AT capacity tho, can't fire HEAT and HESH rounds, so it could only run from Tanks..
And without a system for indirect fire in the game, I suppose a Mortar Barrage from the Reverse slope, wouldn't be feasible in the game..
So I guess you are right, the game just ain't ready for Mortar Barrages yet.