Ive been thinking on this a bit and I think alot of the classified bits go back to foreign heads of state, which is why it cant be unredacted and also why we havent gotten the legally required reason for the blacked out bits. Im of the belief that the law requiring the release of these files was an attempt to make the trump admin look bad. I wouldnt put it past our corrupt congress to try and force Trump into a position where he'd lose face with his base. I could be wrong though, but thats my working theory at the moment.