You are ignorant.
Most animals eat it because it DOES contain enough nutrients and energy to power the mother while they are not able to hunt. It also protects the two of them from predators.
Stop being so preachy. Nature is a wonderful machine. It has thought of everything. Just because you have no predator and plenty of food handy, it doesn’t change to normal equipment you are born with.
I am not ignorant. Many animals do things that are completely disgusting; the claim that because animals do it means that humans should do it as well does not hold water. Many birds regurgitate food to feed their young. Koalas feed feces to their young. Cats lick their kittens' anus and genitals to get them to pass waste, which the mother cats eat. Etc. Eating placentas ranks right up there with the rest of disgusting animal behaviors that do not need to be emulated by humans.
Wow. Good advice; you should take it.