I agree with this. Like how you can trade 4 crystal petrifacts to the ??? (Kupofried) in WoE and they will be converted into a Kupofried's Corundum and added to your stock, you should be able to trade voiddust to a Voidwatch Officer in the same manner.

Another thing that bugs me, is if you are doing a vwnm which you don't need/want anything from (say you're helping friends/ls get clears), and you already have one or more voidstones on you, you either have to actually use a voidstone or you get nothing at all, not even half exp/cruor. Ideally, there should be an option somewhere where you get to pick if you do want to use a voidstone or not.