That's very similar to what I was thinking of last night as wel.Generic vs Customized. Another way would be the generic versions most people skill up on or use at early levels will be a base item with no customization. Mobs will only drop generic versions. Once a crafter gets a hold of it the base item can be configured in different ways, possibly without it being obvious just looking at the item. Custom items will then have Makers Marks on them and the crafter will have a record of what they did to achieve that item assuming a widely interchangeable ingredients system. Mastering the generic item could be required before you can begin customizing it and the challenge quests could be one of the methods of being officially recognized as mastering a generic item and open it up for customization.
Costumizations that ones earned, achieved or obtained can make you stand out. If I knew that there are various design choices out there that can make my creations stand out more, I'll work to get them. (sadly this might only work for gear or house items?) That to me is a subtle challenge and a good motivator to go that extra mile. The requirements might be through the roof, but that would be fine with me. I'll take up that challenge.