While I would agree that God did not want us to be robots but to have free-will in order to have a meaningful relationship with us, it must be noted that Satan, the adversary of God and our very souls, has not been imprisoned on the earth. As is made clear in the book of Job (1:6-7, 2:1-2) he still appears before the throne of God and accuses the saints day and night before God (Rev. 12:10) but eventually will be cast out of Heaven entirely (Rev. 12:7-9) and for a brief time, be confined entirely to the earth.
However, he will eventually be imprisoned in the abyss when Christ returns to reign as our King. (Rev. 20:1-3 ) and then afterward, and after a final failed attempt to overthrow the Kingdom of Christ, Satan, and all those who have followed him, will receive their final sentence when they are all cast into the Lake of Fire. (Rev. 20:7-15)
And if there are other worlds that God has created that have chosen to remain loyal to Him, then why is the universe beyond earth devoid of life? If such worlds even exist, I would suspect that they have already been incorporated into the Kingdom of Heaven itself so as to protect them from the devastating effects of the sin of Adam which has come upon all of creation (Rom. 8:19-22)
And if uncorrupted and unpolluted worlds do exist somewhere in the universe, we would never be allowed to discover and set foot on them because, even if it were not our intent to do so, our very presence on such a world would ruin it immediately because of sin which is ever present within us because it is sin that brings forth death, decay, misery, pain, grief, suffering, hardship, and adversity of every kind that there has been, is now, and ever could be for sin is not merely an act of evil, but rather the inherent corrupted condition of our nature that was passed down to us from Adam and Eve, (Rom. 5:12) the first man and woman God created and from whom we descend and it was in that day that when they ate of that certain fruit forbidden them (Gen. 2:15-17, 3:3) coming from the tree of the knowledge of good and evil, sin entered into them and then was inherited by all of mankind because we descend from them.
And it is because of that one act of disobedience that the present world that we know, with all its evil and darkness, came to be. And if the sin of Adam is responsible for bringing the death, decay, evil, destruction, misery, adversity, hardship, grief, sorrow, corruption, and pain witnessed and experienced in this world, why would any untainted planet want it there?
If there ever are such things as sinless extra-terrestrials, they must be looking down on humanity in both pity and horror.
https://adventbiblestudy67.wordpress.com/questioning-why-god-allowed-sin/