Interestingly, you've pinpointed the exact meaning of "the knowledge of good and evil". It goes something like - I know how I can be hurt, therefore I know how to hurt you.
And if I know how to hurt you(and I'm afraid of being hurt myself), I can use that knowledge to exert power over you. Keep in mind there are worse fates(by far) than death.
So you're asking for a world of beings that are incapable of murder, torture, slavery or inflicting any pain on another - So like a world with only trees and shrubs? That's good?
