Why It Is a Blessed Thing That The Fall Happened

In one of his sermons ("East of Eden"), Jonathan Edwards spends time briefly reflecting upon the blessedness of Adam (if he had obeyed God and been confirmed in righteousness).  He then spends some time talking about why we, as fallen creatures, experience greater joy and blessedness than if Adam had never fallen.  "But there are many things that greatly contribute to the happiness of those that are saved that Adam, if he had stood, would not have had."  I'll bullet-point Edwards' seven things:

1. Saints have union with Christ to enjoy, which they would not have enjoyed if Adam had not fallen.
2. Because of their union with Christ, "they also enjoy nearer relation to God the Father, and are partakers of a greater love of the Father."
3. Christ's obedience, Edwards argues, is a more glorious obedience than Adam's would have been, and therefore was "rewarded with a better reward."
4. Because of their redemption, Christians also share in Christ's exaltation on his throne, "which was the reward of his mediatorial righteousness."
5. Edwards argues that Christians have a more intimate knowledge and enjoyment of God, since Christ was incarnated: "he has taken upon him the human nature and so is nearer to them."
6. We experience a higher manifestation of God's love in Christ.  "This will make all their enjoyments and blessedness the sweeter, the consideration of their being the fruits of such a wonderful love and grace."
7. Finally, Edwards says that as a consequence of the Fall, the redeemed "will have a greater manifestation of the glory of God, God having taken occasion from the fall of man to make a more wonderful display of his glory in the work of redemption. And the more is seen of the glory of God, the greater advantage is there for happiness in the contemplation of it."

Notice the decidedly God-centered character of these answers.  It's just another thing which makes Edwards such an admirable thinker, worthy of emulation.