Talking about Sphene, her end goal is basically eat all life in the universe, which make it impossible for you to have any kind of feeling about destorying her people because there's no good end to her plan. Take the Ascians as comparison, they want to destory the world, but the reason is they want to restore it to the paradise it was. All of us that will die are actually just fragments of the people that lived back then, so in away we're not really dying just becoming whole again, in a twisted kinda way. That makes you feel something, there's a good end goal to their plan. The endless are basically just a fatal parasite that the writers are trying to make use feel bad about removing. If there was a certain amount of souls she needed to consume before her people would be restored to life etc it would be slightly different but nope just consume all life in the universe. It's basically a juvenile attempt at exploring nihilism and consumerism.