Imperfect, Yet Understandable?

I'm reading the Flood story in Genesis.  I was trying to justify the Flood, since I reasoned that God is perfect and thus his acts should inspire me, as they inspire so many evangelical Christians who read the Bible.  But I had a hard time arriving at a justification for the Flood that satisfied me or made me feel good.

Then, I considered: Perhaps I am right to feel sad about the vast bulk of humanity and animals perishing in the Flood.  God himself may have regretted sending it, for God promised never to send another Flood again, and God resolved to put up with humanity's sinfulness after the Flood had subsided.  God even put his war-bow in the sky, perhaps as a sign of peace that indicated that he would not wage war against humanity.

Once I considered the possibility that God in the Bible was not absolutely perfect, even his sending of the Flood appeared to be understandable.  Extreme, mind you, but understandable.  God regretted creating human beings when he beheld their corruption, their violence, and the way that the boundary between humans and the divine was being breached, as the sons of God married the daughters of men.  God appreciated the one righteous man he could find.  Perhaps God went too far in wiping out most of life with the Flood, but God's love for righteousness and disgust with wickedness was understandable.

There are Christians who will have a problem with what I just wrote.  They claim that God changing his mind is not literal but is figurative, for God is perfect and does not need to change his mind.  Why can't they take the Bible at face-value, when they criticize others for not taking the Bible literally, in areas?