Humans and the rest of the living races are the most similar to us, the players.
This being the case, we tend to evaluate both them and the Forsaken from our Human perspective.
In such a situation, isn't it guaranteed that we'll side with the Humans unless we specifically decide to distance ourselves from our own values and experiences and instead look at the relation between the two with neutral, outsider eyes?
Hypothetical situation/Thought Experiment:
Imagine the Humans (whether us or warcraft humans) were transplanted into a world where they were the only animal life. All other life is plant life and it is all sentient life. They all convert solar energy into food energy to survive. They also happen to be the only thing that's edible on the entire planet and the humans have no way to leave the planet, nor anyway to synthesize a new food source.
Now, they don't need to eat humans to survive, but the humans need to eat them to survive.
1. How do you think they would characterize the humans' survival needs? As necessary or as abominable and evil?
2. How would the humans view it?
3. Should they all just die out rather than kill to survive?
4. Should they not have children in order to neither burden the child and the plant life with the cost of their survival?
5. Is it evil to do what survival of you and your species requires? Or is it outside moral definitions?
Lesson:
It's easy to condemn another lifeform for needs you don't share.
It's even harder to objectively look at the situation when the need they have is you.