[donmeaker]

Fact1: Armor costs money.
Fact2: Armor replaces payload.
Fact3: A truck that can carry 5 tons net, can carry 2.5 tons of armor and 2.5 tons of payload, or and combination up to 5 tons.
Fact3: Better than armoring all trucks (5 tons of goods is a fair amount, 5 tons of armor is a misleading inadequacy) is to arm a lot, armor a few, and have the armored and armed trucks escort convoys.

Fact4: None of this is new. IEDs were used by German anarchists against US trucks occupying Germany after WWI. And again after WWII.

Fact5: Field modifications tend to add armor, which is passive, and wears out roads and running gear even if noone is shooting at you. Army planned modifictions tend to add more weapons, which only cost money when they are actually shot, but have no effect on mines, or remote IEDs.

[Wiz]

Fact 6: Soldier's life is more important than the cost of the armor
Fact 7: Adding a more powerful engine will give extra payload to cancel the decreased payload by the added armor, and the DOD have done this
Fact 8: there is no such frontline in Iraq, everywhere could be a battle field, and mortar rounds could fly from miles away that may damage vehicles as well.