…why can’t U.S. soldiers change on the fly, depending on their changing mission?
Apparently, they soon will be able to, according to this recently-updated solicitation, which begins:
The Soldier Protection System is…designed to be worn for both mounted and dismounted personnel during operations against renegade organized factions, terrorists, snipers, criminals, looters or any person, element and hostile groups abroad or within the U.S. The SPS will provide the Soldier multiple levels of ballistic protection that can be tailored to select mission profiles and protection against specific threats from conventional fragmenting munitions, small arms ammunition, and blunt impact. Soldiers equipped with the Vital Torso Protection Sub-system of the SPS will benefit from the versatility of the integrated system that will enable the Soldier to quickly transition from one mission type to another without degrading the momentum of small unit operations.
Emphasis delightfully added.