There are already specific tasks for Nightmare.
The collection log shows the rates per specific piece, with there being more than one drop in each section this is then as shown:
1/500 For an item / 4 of these items in the table / 4/500 for that table / 1/125 foe any item.
Kills take a matter of minutes to solo, not to mention the boss being heavily nerfed. It is not only semi-afkable but easy to kill, and this is pre all the new vi's items that have more recently been added.
The idea to include nightmare within the vampyre tasks is a no.