Why can we have something like the notes, that is when you load a document then initially the child table (item table) is non-editable, but the moment you click the edit button the whole table becomes editable showing 4-columns only.
This ways we are only increasing 1-click for adding all the items from the current scenario but it would bring back the old functionality where we could see all the fields which are marked as SHOW IN LIST. See the gif below which is nothing but a NOTE in v6.
Now see a lot of users are already using the show in list view property and removing this feature would only encourage these people not to update, see the image attached.