Why Introspection?
As Christians, we believe that, "If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness." ( 1 John 1:9 ). So, why then should we make "a searching and fearless moral inventory of ourselves"? Doesn't God just erase our past? No. He forgives and cleanses, but He doesn't give us amnesia.
It's been said that, the most powerful thing we can do for the kingdom of God, is to witness to others of the way that God is working in our lives to heal our dysfunction. If that's true, then how are we going to do that if we can't remember what our dysfunction was? How are we going to overcome, not only by the blood of the Lamb, but also by the word of our testimony ( Revelation 12:11 ), if we have no testimony of what we used to be like?
I know that, for me, I have a choice. Either I can choose to continue to evaluate my life (and deal with it), or I will revert back to the insane cycle of repeating the same negative behaviors over and over again, while expecting different results.
"Take heed therefore that the light which is in thee be not darkness. If thy whole body therefore be full of light, having no part dark, the whole shall be full of light, as when the bright shining of a candle doth give thee light." ( Luke 11:35-36 )