If an animal is made extinct or less populated by other animals eating them or destroying their homes, how is that different to people doing the same thing to animals. We are doing what comes naturally to us as well. We have a natural instinct to disperse and consume, and that causes some animals(the weaker or dumber ones) to become endangered/extinct. I don't see the difference.
Mother nature corrects her own wrongs. If we reintroduce species that are endangered/extinct, and they die, we have lost nothing but our effort. If we do nothing, a species is wiped off the face of the earth. Besides, why clone animals like sheep, but not the animals that need more numbers?