Do we remember that it's because of God's lovingkindness that He forgives us? It's not because He's obligated to. And it's only because of Christ's work on the cross that we are even able to come to God for forgiveness.
8 Good and upright is the LORD; Therefore He teaches sinners in the way. 9 The humble He guides in justice, And the humble He teaches His way. 10 All the paths of the LORD are mercy and truth, To such as keep His covenant and His testimonies. 11 For Your name’s sake, O LORD, Pardon my iniquity, for it is great.Only God is good. He is the standard bearer for us to follow. We must be humble to follow Him, because the proud don't think they need forgiveness. And in verse 11 it's made clear that God does this, forgives the unforgivable, to display His glory, and mercy, and love. Praise be to God!