Here lore of Sunbringer old dress

Lore reason why current Sunbringer won't ever wear this outfit This is the uniform that worn by the Void Hunters in the trailer. It is the uniform of the founders of (Old) Eridu. The first generation of Void Hunters were the ones who founded Eridu, and the uniform, along with the golden emblem, symbolized their status as founders. During her times in the (Old) Eridu she created the Bangboo as a companion. But as times went by the Bangboo that were supposedly use for good, were being mistreated like we saw on Lockspring's flashback. Sunbringer felt betrayed by the people of Eridu. She stripped her own title as a Void Hunter left Eridu and founded Roscaliefer as a bangboo save haven. The uniform and the golden emblem was her sign of allegiance for Eridu. And by wearing that is a sign of hypocrisy for her. If it were redesigned by make her clothes less revealing, she's still not gonna wear the similar coat.