The Commissar points out a lack of malice or even ineptitude on the part of the DOD with the 'unarmored humvee' claims:

Why do our soldiers have unarmored Humvees in Iraq? What are we doing about it? How many armored ones do we have?

In World War Two fighter planes of all types evolved in a common way. The first model was designed to a certain spec, to fly a certain speed, powered by an engine of X horsepower, carrying X weapons, and armored to some extent. Subsequent models invariably included: more weapons, more armorplate (especially around the cockpit), bigger engines, and better self-sealing fuel tanks. For example, read about the development of the P-47 Thunderbolt. All this development came at a cost. With bigger engines and a lot more weight jammed onto the original airframe, the planes became much harder to fly, much tricker to handle, more likely to flip over on take-off in the hands of an ordinary pilot.

The analogy to the Humvee is imperfect, but useful. The Humvee was designed 20+ years ago to be the military's all-purpose vehicle.

GRTHT*.