The Subject At Hand
As I've mentioned before, crafting is something I find to be a significant draw in an MMO. If the crafting system is boring, the rest of the game will have to strain itself to keep my interest. Only WoW has been able to survive under the weight of having a bland crafting system, thanks in part to my guild and some undetermined something that WoW has that keeps me.
Today, I will define aspects of successful, interesting crafting systems. On its own, crafting can be fun in its own right, but these features, when added, can improve the overall experience greatly.