Few Christians believe that God is affected by the actions of his creatures, but he is. When people understand the view of a passible God, their appreciation for God and their understanding of God’s action in the world will grow.
I think that this is important! Yes, God is transcendent but that does not mean that he does not feel our problems and that our sin don't affect him. Our sins don't limit him but it limits us and our ability to relate and commune with our creator. It is this fact that is missed when people ask why God cares about what we believe or why he cares about what we do.
For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. - Hebrews 4:15
Dr. Claude Mariottini - Professor of Old Testament: The Passibility of God