A useful way to read plate carrier evolution is as a continuation of a very old story: the contest between protection, mobility, and the dominant wounding mechanism of the era.
When massed musketry dominated, armies leaned toward formations and drill rather than personal armor. By WWI the battlefield shifted toward artillery and fragmentation; you see renewed interest in helmets and partial body protection because shells, not rifles, were doing the bulk of the killing. WWII and Korea reinforce that point—fragmentation and blast remain decisive, and doctrine emphasizes fire/maneuver supported by heavy weapons.
Modern plate carriers are being pulled by a similar reality: in many recent conflicts the casualty driver is still fragmentation (artillery, mortars, grenades, IEDs), while small-arms lethality persists. That creates tension: plates are great for certain rifle threats, but soft armor coverage matters for fragments, and yet soldiers also need to move, climb, mount vehicles, and fight in close terrain. Add the late Cold War/early GWOT trend of “carrying the war on your body” (more comms, batteries, optics, medical), and you get today’s emphasis on load management and modularity.
So the big trend isn’t “minimalist vs heavy” as a single answer—it’s tailoring. Units try to scale protection and carriage to mission: dismounted patrol vs vehicle-centric ops vs trench-like artillery environments. History suggests the pendulum will keep swinging with the threat environment, just like it did with helmets, flak jackets, and web gear.