Hey John,
The baseline armour is deliberate - you want to run the vehicle in training at as light a weight as possible - it reduces running costs and wear and tear on the vehicle. You can electronically retard the engine so that it doesn't run like a racecar being so light. You then have a series of deployment armour kits tailored to the scenario you deploy to - high kinetic threat, high IED etc. You fit the right kit where required. Armoured Knights didn't wear all that plate armour all the time - only when required.
The other contender is the Rheinmetall Lynx - both vehicles are what the Army asked for way back in 2015 when they released the Request For Information - Hanwha and Rheinmetall both built brand new vehicles to what Army asked for. Either will be awesome compared to the M113AS4.