Its worth noting that Hydealyn seems tied to the world's Aether and as that diminishes she has too. She is supposed to be the wellspring of Aether in the world which is why the world shares her name and she is known as the Mothercrystal. Its possible that Aether consumed by Primals doesn't return to the natural cycle of Aether in the world. Regardless its bad for us cause Aether equals life so if the Aether starts to run dry eventually it means the land will die as well.