I like the idea of the faction war, but the delivery is usually so bad that it seems pointless. Every time the Horde has a leader dark enough to make them different enough from the Alliance to justify the war, the rest of the Horde rebels against the leader and gets help from the Alliance to overthrow them. If both sides are good then there is no reason for them to be fighting, and any sense of faction identity is long gone thanks to some of the races added over the years.