I think the main issue is unlike any army, GW is really balancing 3 armies with Nighthaunt. LoN, LoG and Nighthaunt. This makes balance, ridiculously hard. As we know, Grimghasts were fine in NH, but broken in LoN. Now they have to balance points to account for LoG as well. As long as this exists in this current form, I think Nighthaunt will likely never be balanced as a solo tome.