Really? Common harvests are considered a reward for the research missions? This would be bad if there wasn't a 3-hour time sink in between quests. It's bad enough they are reverting back to making advanced books harder to get.
People were complaining that they were getting too many nails, but the itemization folks decided that the drop rate on recipe books was already perfect. The compromise then was to replace nails with other things. The only things a tradeskiller might want beyond nails and recipes was common mats, specifically those from nodes with multiple drops (dens, bushes). /just the messenger
I'd have agreed if it wasn't "common" mats. Someone looked at 35 common mats and thought that was an appropriate reward for a mission.
The "appropriate reward for a mission" is the token currency you gain to buy various items and recipes. The nails and resources are just filler in the reward bag so you get "something" else while waiting for the RNG to drop you a recipe. Rare resources would not be considered filler, but something more valuable, and would then require changing drop rates on everything, including the recipes. (Thereby reducing your chance at getting a recipe, which is not what is wanted.) This was the compromise so that players got less of the nails that they were complaining about, and instead got some resources that they could burn instead, while NOT changing the rarity of the recipes. As always, we cannot please everyone with a compromise.