The nations that are playable in custom battles have their own uniform models for soldiers. Other factions use generic models and have generic units, and as such it's pointless to have them playable in battle as the only thing that changes is the country flag.
don_durandal
Mic joined
I am an amateur texture artist working for mod projects in my spare time. Currently I am the lead developer of “The Great War 1918” team, a WW1 modification for Company of Heroes (as texture artist, historian, designer and code monkey). I also assist the Verdun Online project as historian, an indie FPS game project set in WW1. Amongst other projects I made textures for "His Righteous Mod" (under the nick Grenadier), a modification for Dawn of War.