That is a great question. I think, in my personal opinion, that since most religions, including JWs, have redefined faith as blind obedience, it lends to this type of contradictions.
The bible tells us of the several occasions in which God had it with humanity and was ready to wipe them all out. Not just at the flood, also during Moises' time. Moises, however, appeased him. He told God that his fame as a loving, redeeming God would be ruined in the eyes of humanity if he killed the Israelites after he miraculously freed them from Egypt. This, in my view, has little to do with being an all knowing God. Is more about faith. In my view, faith is like a modern day credit report. When you go to a bank to take a loan, your approval would be based on your history. Basically the bank would demonstrate faith in your responsibility as a borrower. Provided we are talking about a personal loan with no collateral. When it comes to spirituality, never in the bible it speaks of blind faith. Most of the faith shown by the people of the bible comes from a- past experiences in which God fulfilled his promises and b- based on demanding that God showed them some sort of miracle so that they would believe in his power.
With that said, and based on what I understand from the bible, God would have to have reasons to have faith in humanity. When he has lost it, he attempted to start over, always leaving a handful of humans around to see his power and redemption from evil. This, in my view, would not necessarily be bad. If humans are made to his image and humans are capable of losing faith, then God is very much capable of the same thing. You could, may be, say that the difference is that we humans can loose faith for the wrong reasons while God losses it for the right reasons. I would leave that up as something to be speculated upon, since we have this idea implanted on us that the word "perfect" is literal as it appears in the bible when referring to God.