It is necessary to preserve original documents for use by historians in the future. These are the absolute primary sources and should be maintained.
The issue with the current occupant of the White House and his adminstration is their overwhelming concerns with secrecy and keeping information out of the hands of the general public. Hence, the lengthening of the time that Presidential documents are to be withheld from the public.
As to usefulness, a few years back, Michael Beschloss published a book of transcriptions of telephone conversations made by Lyndon Johnson while he was President. The technology was extremely primitive but they were able to do a pretty good job on transcribing everything.
It’s fascinating reading. Really!!!. Listening to Johnson use his powers of persuasion and the power of his office to manipulate legislators into coming into his corner on issues like the passage of the 1964 civil rights bills. A great book.
Along the same lines, but from different circumstances, is the book “Plain Speaking” which are transcribed conversations with Harry Truman that were done by Merle Miller in the mid-60’s. Good way to get some insight into Truman.
The book was not published until just after Truman’s death in ‘72 or ‘73/.
SRM