The 1.0 White Mage questline seems to indicate that it was Oha-Sok, the collective rage of the Elementals, who unleashed the floods that devastated Eorzea and the reason being the gross abuse of magic. Also what seems to anger the Elementals is the abuse of nature. Whatever they are they do seem intrinsically tied to the natural world. This story is full of shades of grey. Calling the Elementals abusive would be ignoring that the acts of man have harmed them. Lets face it. The natural world has taken one hell of a hammering in FF14 and the majority of it seems to be at the feet of playerable races even if not the particular groups our characters associate with. The Calamity was entirely the work of men.