Venat/Hydaelyn is a Mary Sue. Her reasoning was if those that attain perfection just want to die then everyone must be unable to attain perfection but always strive for it. While Zodiark was presented as a choice. The sundering caused by Venat was not. She chose that for everyone without even communicating that was what was going to happen. And only a select few were able to avoid it. Elidibus, Hades, Lahabrea.
I find it amusing that Venat/Hydaelyn is always praised for her actions and never reprimanded for them save for the WoL. Because while they say Hydaelyn never tempered anyone I feel that a majority of Eorzeans are tempered to Hydaelyn but not in the typical sense. As to them Hydaelyn never does anything wrong.