To be more correct that would not be a hoplite... that is a centurion (roman soldiers using adapted greek strategy/armor/arms)
Most hoplites did not wear full chest armor, usually a brestplate, or at most leather armor.
Berserkers are nordic frontline soldiers, known for wearing only pelts, and not much of it.
Zulu warriors wore barely a codpiece, and were quite successful at combat.
Blackfoot, mochican and several plains indian tribes....
Picts and gaelic/celtic tribes fought in little to nothing.
Most of these armies where more successful than more heavily armored troops, and this is only the start.
Really the only icon you could use Xenobia/Senobia/Zenobia (dependent on translation).
The historical offtopicness:
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None of those warriors would be like "oki, half of you go heavily armored, the other one of you gets to wear cute pointless armor". Or in a modern army/police go like "okay guys, here are your uniforms: camouflage clotheing and a bulletproof vest. Here is your armor girls: cute colors, and we removed the bulletproof vest so you can show your belly" xP.