I think it would be very confusing if the I-function were always aware of how the brain was reconstructing reality.  I can’t imagine going through the world always thinking about how I should perceive it.  It would be far too distracting.  If the I-function were directly involved in the process, we’d always be occupied with how we should be viewing the world.  And we’d probably always be questioning whether or not we were making the right choices of what to see and what not to see.  What if everyone chose to “fill in the gaps” differently?  True, we don’t know for sure that we currently fill them in a similar way, but I assume that since it’s automatic, there is a certain amount of pre-programming involved.  We may not all see the exact same picture, I think we probably see similar ones.  But if the I-function were involved, would it be possible to choose to construct very different pictures?  Would anyone be able to communicate their perception of reality to others?