I'd go a step further. Without evil, there could be no good. To be capable of one is to be capable of the other. Without the Ted Bundys of the world, there could be no Mozarts. Without Mengeles, there could be no Salks. Without Hitlers, there could be no Washingtons. Even natural disasters play a role. How much of our technology that makes lives more enjoyable is the result of our attempts to avert destruction by nature?
Frankly, this works whether or not God exists. As some who believes God exists, however, I have to conclude that God set up the world and human species to have free will, which is our potential for evil. Whether He personally introduced it or not, it was His intent that evil exist. It had to, if we were not to remain mindless animals.