Why do many older coats of arms have simple designs?

In the context of heraldry, the simplicity of older coats of arms was a functional necessity rather than an aesthetic choice. During the 12th century, these symbols were primarily used in medieval warfare to distinguish between mail-clad knights on the battlefield.1

Because most people at the time were illiterate, armorial bearings needed to be bold, striking, and easily recognizable from a distance. A simple design allowed combatants to quickly identify friend from foe, a critical distinction that could mean the difference between safety and death. Furthermore, the tinctures (colors) and patterns were governed by principles of visibility—such as the rule against placing a color upon a color—to ensure the designs remained distinct even in the chaos of battle.12

While later centuries saw the rise of "the Decadence," a period characterized by overly intricate and esoteric designs, the original medieval style prioritized clarity to serve its utilitarian purpose in combat.1