The Tree of Knowledge gave Adam and Eve the knowledge of both good and evil. The account starts out with noting that all God made was good. It was like Adam and Eve said, "All this good is nice and all--but we want to know evil, too." In Orthodox Judaism, the story continues with God agreeing to their decision, and the Tree was planted. In this Orthodox version, Adam and Eve were told not to eat the fruit because the fruit wasn't yet ready. In remembrance of this, some Orthodox do not eat fruit off trees is not eaten until the second year it produces.
The consequences of partaking that which was not quite ready to be consumed began to be felt. God basically explained, This throws things off and here is what we face in the meantime--but I am not throwing in the towel. I am sticking with human desire to know both good and evil. I will bring things back around.
Some believe God accomplishes things in the time it takes to snap one's fingers. I believe it is more likely that God takes time with all of His creations.
The question to ask is, How many of us would choose to know only good that exists and to be shielded from knowing about any evil?
God knows evil exists--and He also knows how to make good come from it. How many humans think having this knowledge would be a plus?