They had to have free will to make the first choice. And afterwards, they still had free will to follow God's Ways or not, just as it still is for us today. Otherwise, our making a choice to believe on The Father through His Son Jesus Christ would be meaningless. We all could question God at the Judgment for why He made us do this or that.
This is a major principle that makes Christianity different from most religions of the world. The world's religions are about the idea of force against one's will, especially Islam. The fact that the Christian nations still allow those of the world's religions to follow what they want while only offering The Gospel through choice reveals this.
If you understand what Christ's coming Millennium reign is about, with the nations being made to bow to Christ then, but still... given the choice to not follow (like the end of Zech.14), that again shows God is long-suffering and wants everyone to come to repentance, but will not force us to.