Virtues of the Houyhnhnms

I thought it was interesting that "friendship" and "benevolence" were the virtues of the Houyhnhnms. In England and the rest of Europe during Jonathan Swift's life time, those attributes were probably hard to come by. That must explain why Gulliver distances himself from his family when he gets back to England. I think that Swift includes these virtues to explain to the reader that there will always be people in the world who will be friendly and benevolent, despite everything else you experience. Think about it: you can't have darkness without light or badness without good. That's what makes the world spin.