Roman Full Plate Armor?

[Sean Manning]

I mostly share Matthew's views here. Common soldiers wore body armour, a helmet, and maybe one more item of armour, because it was affordable, not too heavy on the march, and gave them a good chance of surviving wounds in combat. Medieval knights had more money, and servants and pack-horses to carry their armour, so they wore more of it. We do see some Roman cavalry in nearly complete armour, and my impression is that such cavalry get more common as time goes on.

The one disadvantage of well-made full armour I can think of is that men and horses in full armour will tend to tire and overheat faster. But many armies located in hot regions like Southwest Asia have felt that heavy armour for cavalry and charioteers was worth the cost.