From evangelicalrealism.com:

The free will defense does more than compromise God’s omnipotence, however. It also compromises His omniscience. Why predict a future that you know will never happen? If you’re an all-seeing, all-knowing God who controls the future or at least understands what it’s going to be, wouldn’t your prophetic air-time be better spent on predictions that were actually going to come true? Or does God not understand the human heart well enough to anticipate the degree to which man’s cooperation will be present or absent?