Why does it need balancing? Yes a lot of factions get killed off (yes playable ones as well) but so what? The fact is other factions seem to rise and keep pace with the players growth very well perhaps even better so it keeps the game fun and challenging. I have yet to see any faction completely run away as happened in previous TW titles here there are a number of factions that do well ... if the AI was not allowed to grow basically in the interest of keeping everyone around, who would be in a position to challenge the player as he has continued to grow unimpeded.
From what I have seen this is hands down the best TW title ever ... now Japan might not be your cup of tea but that is not the same thing as saying the game is not good.