It was a good movie. Except that absolutes line ruined the scene. Not just because of my conservatism, either. The whole audience let out snickers and snorts of derision at this contradiction. It destroyed an otherwise moving moment.
I agree, but remember, if you think about it, Obi Wan badly misjudged Annakin---so he ISN'T "all wise," and he doesn't know everything. That's what I took out of that line---another bad call by Annakin.