I personally feel that it is enough that you can mod the game to make all factions playable... Heck, you can mod in a whole new game.

If any of you do enjoy modding TW like I do, wasn't making all factions playable also your first mod? It is the hint. "Come on, try to make them all playable..." and then you discover this whole MASSIVE game engine. And this engine makes the rest of it (the factions, the units etc.) almost irrelevant.