You sweet summer child...
1. The Sundering affected just about everything, including memories. Ergo, it was an effective death of personality; even if the body survived and the soul lived on (albeit diluted), the person would never be the same due to lacking their memories from the time of Amaurot. Wouldn't be so different to reducing modern people to caveman intelligence with a Thanos snap or something; wouldn't have a clue what was going on, and would have to build civilization back from the ground up.
2.Lol so you care more about cows than people?Ahem... it's not stated what they intended to sacrifice to Zodiark to release the original sacrifices' souls, but the common hit against this is that since we don't know for sure as far as anyone can tell it would have just been wildlife or livestock. The fact a soul is a precious gift from the planet and turning it into a disposable commodity is extremely questionable, and that these commodified souls could be reincarnations, and the new lives potentially being sentient, have been deemed inconsequential.