In today's Gospel, Jesus instructs his disciples to take swords, but when later his enemies come to arrest him, he rebukes them for using the sword. So it seems clear that he wanted them to have swords but not use them, perhaps as a token of his own humiliation: that he had the power to keep himself from crucifixion, but he chose not to use it.
And yet the plan was ruined because one of his disciples drew the sword and cut of a man's ear. But then Jesus heals the ear, and the end of this event is wondrous to behold: it is better than it had been without the breach.
So also, when God made the world it was very good. Yet sin entered in, and evil engulfed the world. Now God enters the world and redeems it by his blood. This will make the last paradise better than the first.
Thus there is never need to regret past sins or their consequences. God's healing redemption makes the end result better than the first.
So then, is it good that there was sin? May it never be! But God's mercy is so great that his healing of a breach makes the last bond stronger. Let us rejoice and be glad. The sermon.