The universe was perfect before man was created by God. Why didn't God just leave well enough alone?

Like a novel, the history of the human race will eventually end and God knows the ending, it will be perfect. God allowed sin and evil to enter our world because He wanted us to participate in the evolution of our world into perfection. Maybe it is very hard for you to accept, but God is in control even of the evil He allowed to happen, He simply knows that it will result to a greater good.