Just something that has been rattling around my head, and I must say I'm not sure exactly what I should search for to ensure it hasnt been discussed before, so if it has been and I missed it, I am sorry

Now, it might seem wrong that you do not level a crafting profession by using it, since that is at least one important aspect of gaining a skill in the real world. But in in games, this comes with a bit of a problem or at least side-effect.
When you level by using a crafting skill, people will end up crafting things no one needs, no one asked for and that there is no real market for, just because it gives them experience.
In such a system there is additional value of the craft that comes not from the item created, but from the secondary (and in some games tertiary) benefits of that craft. While this works, it tends to have effects on the value of items/resources that at least I personally find immersion-breaking.
My point here was mostly to point out the issue as it were, not really to suggest an alternative.
After all I am not really confident in designing the best replacment.
But just to show that there are some here is a list from the top of my head:
- We have EVE Online's version were you pay the gold, and wait IRL time for it to be ready.
- You could have a version like how you improve skills in skyrim, pay an NPC(or a menu?) gold for each level. That way you would focus on making money to invest in your skills.
- You could also craft things, just not things that have any use. While this will affect market prices, it wont do so in the same way.
- You could try to work with minigames, or "cultural exhange" where at certain points you need to "discuss" things with another crafter of the same trade and skill to move forward.
That said, pardon my braindump as it were