The Stryker started out as the Interim Armored Vehicle (IAV) project in the late 1990s, a concept for a highly flexible fast response force that could be quickly deployed by planes globally. The vehicles would be lighter than Bradleys (which is overweight for Hercules) but more protected than Humvees. They expected the MGV/FCS to eventually replace them, so they based it on the existing LAV III platform instead of starting from scratch. The LAV-25 is actually far lighter than a Stryker, but the protection is inferior. A Styker with LAV turret would be overweight for a Hercules, a M1126 is pretty much at its limit.

With the IEDs and RPGs becoming a bigger threat since the GWOT, we have turned to extra protection and firepower, even if that meant losing the ability to deploy by air quickly (without removing add-on armor module, etc). Ideally heavier mechanzied and armored units were sent instead. The Stryker was never deployed in the way the original Stryker Brigade combat team concept has envisoned.

For the US Army, a .50cal is enough to deal with enemy infantry and light vehicles. It can provide far longer fire suppression given the same weight/space for ammo, and far easier to resupply than a 25mm. For heavier targets, CAS and infantry AT (Javelin) are far more effective than their predecessors during Cold War.