Why the Lord Ruler Created the Kandra as They Are
You may have noticed something in this chapter. TenSoon mentions the food pits that the kandra people cultivate, a mixture of algae and fungus that they grow in holes in the ground. Yes, they can survive on this. No, it doesn't taste very good. However, it doesn't need light to grow.
Humankind couldn't survive on this mixture, unfortunately. However, one thing that is never brought up in the text is something that not even the kandra know. There are several reasons that the Lord Ruler created them as he did. One of those reasons was so that there would be a people who could survive beneath the ground, should the world above be destroyed by the mists. In other words, he created a race of subterranean dwellers to outlast humankind, should that become necessary. He was the one who gave them the Homeland as their inheritance and taught them to begin growing food that would survive underground.
Then, of course, he decided to add the Resolution to their code of law. That was a precaution in case Ruin decided to claim them as his own. A bit self-defeating, true, but the Lord Ruler felt it was better for them to die than to become pawns of his most dangerous enemy.