Hey, man, don't worry about the downvotes too much. Even though I completely disagree with you, you are right to have your opinion.
But, because I'm an armor and weapons guy, I must make one little correction for you. Pantheon's armor is fine. The reason why he can get away with have little to no leg armor (as the Ancient Greeks didn't). Is because of the shield.
So, when fighting in formation, on foot, as would be the case with Pantheon since he was originally just one of many soldiers of Stanpar (before the great lore retcon). When moving in that way it's really hard to aim and strike at the enemy's legs with weapons, because, you attack through your arms which are all on the top of your body. So to strike low means you have to expose your neck and shoulders to an enemy striking high who now has longer reach than you because your neck and shoulders are closer to his arm than his legs are to your arm.
This is further enforced with having a big shield such as a Scutum, or a Round Shield, or, as Pantheon uses, as Aspis. These were held out in front of their torso and dipped low enough to their knee. Which, because their feet were back behind the shield makes striking at their legs, if not impossible, highly unlikely.
We actually see this style come back in Three-Quarter Plate during the Late Medieval Period, like this:
https://c8.alamy.com/comp/BRFXA5/a-black-and-white-three-quarter-armour-nuremberg-circa-154050-burgonet-BRFXA5.jpg
This type of armor was usually used with a shield and with no actual armor on the lower legs. Though sometimes halberdiers would use it too, but that's in part because foot armor is really expensive. Honestly, one sabaton costs about as much as a front and back plate. Making the lames fold in each other properly so you can move your foot and not have it just into your skin was difficult.