I thought it might be neat if the crafting classes could have cultural expertise, for example Culinarian could learn to craft in primarily Ishgardian dishes, or Doman etc. Certain cultures would have more access to stat boosting specifics like Gridanian giving bonuses to nature resistance or Ul'dan dishes giving a bonus to earth or fire.
This could be used as an interesting "skin" feature as well, custom made mythril armor or weapons as an example, fashioned in Limsan design for the aspiring pirate.
Would probably be better for long term game play if you had to choose one or two specialties per craft instead of wide range access to all, as it would diminish the uniqueness of being a "Master Ishgardian Blacksmith".
These specialties could also include character perks as well such as improved accuracy for Gridanian bows, or increased spell speed when crafting Sharlayan tomes or grimoires, which could help players decide on what to choose based on their main class.