I don't know how hard this would be to implement, but I think it's worth discussing. First of all, more NM's should be added to the list, even to zones that already have a NM target.
Once you complete an objective, the drop becomes available to purchase with sparks. So let's say you complete the objective for Valkurm Emperor. Get the hairpin? Great! No drop? Well, you have to choices: camp the NM again, or, the hairpin becomes available to purchase from the RoE NPC now that you have the objective completed. I think drops should still cost more than the NM awards you, but it would be an alternative to get the drop.