What a good article! You are very careful to present just the facts, but I think you make very strong cases here. Of course, you're preaching to the choir.
I have seen a mare whose foal was euthanized run in a frenzy up and down the field, calling, and calling for her child. I have seen crows march around a killed flock mate. And those same crows never forgave the foolish fox that killed the crow! They mobbed the fox wherever it went and spoiled its hunting and its life.
At the other extreme, I had parakeets, and when one of a pair passed away, it seemed to be no big deal as long as they had another parakeet to be with. If you're not with the one you love, love the one you're with. I guess people encompass both extremes, too, come to think of it!