I don't have to convince anyone here that this is a very often cruel and imperfect world
Not a great presumption, as you many need to convince me. I do not believe in some objectively existing good/evil dichotomy.
Thus when posited the question "...then why is there evil in the world??" my answer is "There isn't."
Good and Evil are, in my view, man-made ideas to try to categorize things in the world. They are invented in the mind, nothing more. I believe that adopting the notion that they exist is a mistake.
Nietzsche wrote a book about this mistake,
Thus Spoke Zarathustra. In it, the prophet Zarathustra, whom Nietzsche believes to be the first one to separate Good and Evil into a dichotomy (his understanding of Zoroastrianism was not that good), and thus he writes about the prophet's repentance, having him preach against that dichotomy.
Lao Tzu seemed to view the creation of the dichotomy as an abandonment of the Way.
Tao Te Ching said:
When the Tao is forgotten, there is righteousness.
When righteousness is forgotten, there is morality.
When morality is forgotten, there is law and ritual.
Law and ritual are the husk of true faith,
and the beginning of chaos.
Righteousness, or what is right/Good, arises when we forget the Tao.
Morality, or what is wrong/Evil, arises when we forget Righteousness.
Ritual is born when we forget Morality.
We even can see parallels, I believe, in the Abrahamic Creation myth. Mankind exists in Eden, a world without evil, alongside God. Man goes against God, and eat from the tree, attaining "Knowledge" of what is "Good" and what is "Evil". They invent the dichotomy and begin separating Good from Evil, labeling their own nudity as Evil. For this sin, they are cast out of Eden, the world without evil, into a world where Evil exists. I feel this is metaphor. They are cast out of the world without evil not as a physical act, but merely because they invented Evil. And now they exist in a world of evil. But it is evil only because they have labeled it that way.