Not too long ago, maybe a year, a friend of mine from this site who you all are familiar with in some way and who is famous for his controversially elevated opinion of his type was explaining to me a theory which ranked the NT types according to their impartiality.
Since I haven't consulted with him about this thread I won't discuss what his theory way specifically but suffice to say that he chastised Fi using NTs for having an even more partial form of F.
At the time I thought it was a little silly but I'm starting to warm up to the idea.
Fi operates in me as a sort of on/off switch that makes me either support and idea or oppose it. It is reponsible, I think, for the clear disparity in quality between my criticisms. When I am forced to criticize something which my Fi is indifferent or positive towards, it takes a force of will far greater than when Fi opposes the subject.
While I have often deceived myself as to the reason for this phenomenon that could very easily be classed as morality(and may likely be deceiving myself even now), I am confident enough now to say that it is simply the partial reaction of my Fi which aligns me to a cause and not any higher, idealist cause.
However pessimistic this may sound, in the end I believe that Fi's aggregate benefit to me through motivation will be greater than it's negative effects.
So yeah, Fi makes me dumb but it makes me happy also.