The docking tube isn't added, it's just made bigger. It wasn't tall enough to get one human through, so in the name of sanity I turned it in to a proper docking tube.
Also, since we're refering to that change, I'd like to point out that I can't really find any evidence that

intended it to actually be a dockpoint. Unfortunately that's where the dockpoint actually is, which is one of the main reasons I've had to redesign the front as radically as I have.
And for those of you who can't figure out where this fits in the big picture, you may find these useful:

