The problem is over saturation of the market. This is something SE wanted to prevent but it happened anyway due to poor planning. Getting 3-5 items per node swing at lvl 50 is WAY too much. Basically the demand for these materials by crafters is vastly overshadowed by the supply from Gatherers (both MIN and BTN). SE has said they will make more recipes for the lower level material gathers but I for one hope they add a lot more for the higher levels as well with more items needed for one craft. Crawler cocoons are the best as OP mentioned and you only need 4 for one lvl 50 craft. 4 cocoons is nothing when I can get 25 from one node, and that's just one person. 25 cocoons times all these gatherers results in a filled up market board. Naturally you could go the other route for 15 NQ and 3HQ (potential for more) but either way results in way too many items and too low of a demand.