Some queries regarding EB's units...

[Rolling Thunder]

To answer your question with a short sentence: balancing the units was more important than giving armour values by skins. I agree this unit stat modding policy of EB team.

And thus realism (and thus historical accuracy) was not so much discarded as it was kicked down a giant well by the king of Sparta.

There are a few balancing adjustments to my knowledge (barbarian units get +1 armour, phalangites get reduced armour and increased shield), but beyond that armour and shield stats are consistently based on equipment. In this particular case: the EB team considers linothorax to be almost as good chainmail, and the standard hoplite wears leather or a linothorax reinforced with metal plates.

I must politely disagree with the EB team. The linenthorax is excellent armour - equal or superior to the bronze muscle cuirass that is replaced - but it is neither as covering nor as effective as chainmail. Unless it is literally immune to sword slashes as chainmail is, highly resistant to thrusts and blunt trauma as well, then it is, put simply, not as good as chainmail. Leather armour isn't even as effective as padded armour (unless reinforced with plates).