So it's surprising and a little lucky that the docs were created as sincerely as they were. The content is pretty good, though not perfect. It could have been a total joke.
But Gene Roddenberry's credo had been to make it feel as real as possible, especially in the 1960's.
I think these on-screen documents are a nice testament to that and put the actors in the "right" mood in a manner of speaking (e.g. Bill Shatner reading "my" report on Talos IV
, obviously not something that would make an actor crack up and start to laugh in the middle of shooting).
It's a little pity they didn't continue this kind of earnestness in TNG, now that the remastering in HD reveals all these little insike jokes, both the silly and the better ones.