I think it’s interesting to note that there are currently 5 playable races and 5 known dragons.
http://i.imgur.com/vKP7D.jpg strongly suggests that in a previous awakening of the dragons, 6 races were necessary to combat the 6 dragons. The Gods seem to want to stop the dragons, but can’t do it directly (the Dragon’s as consumptive foils to the Gods? The more the Gods use their powers, the stronger the Dragon’s hunger is to devour and reclaim that spent energy?).