There’s a chance that, if you haven’t been collecting classic Who on DVD, you weren’t aware that this has been happening. It’s interesting, and at least BBC Video has always included the original material alongside the new instead of making it the proverbial upgrade that you can’t roll back.
Video lasts about…as long as an episode of classic Doctor Who.
“All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can’t get them together again, there must be a reason. By all means, do not use a hammer.” —IBM Manual, 1925