The wicked can be a powerful reminder of your own need to repent and get right before God daily. Also, they are a good barometer to determine whether you have the love of God in you or whether you are only kind to those you prefer. The wicked can also be an example of how an immoral or amoral lifestyle causes death. Examples of this can be found in disgraced Illinois Governor Blagojevich, or baseball players that cheated and used steroids. Finally, it is good to have the wicked simply because without the ability to do evil, no one could truly ever choose The Lord. God just used a cheating girlfriend to relocate me to the church I need to be serving in. He really is infinitely clever.