I think it was mentioned in some other post that they are having hard time deciding what to let the essence pool drop while not hurting economy.
The thing is, if you don't make new items, then all you can do to make the final reward good is to make it drop rare items.But if they keep making final rewards that way, then those rare items will no longer be rare and it will hurt their income.
So why not create new crafting lines (like the horse hair and rope, but they need to make more use of it)?
For example, a cloth shop which players can use to make clothes and trinkets for quest or sell for gold? Some will be required by quest, and you can also make it and sell it to exchange for gold coins.
With cloth shop, then you can create lots of new raw materials for harvesting as well (which leads to more building rewards for events).
Cotton is definitely one, which then you got new planting seeds to grow on farm plot. Wool is one too which will make players to buy more sheep. Silk can be added too, which you can create new silk worms line for players to harvest. Hide from cow can also make leather clothes.
If it can also create jewelry or trinkets, then you got another use of gemstone line and metal line to create.