Don't worry to much about crafting. I did the quest then finished the story before starting any crafts the only advantage to taking a crafting class to 20 is melding your own gear. Taking it to 30 is producing your own dye for modifying your clothing. If you took that long to level your crafting you might not know about "basic touch" adding to EXP gained from each craft. As quality goes up so does your EXP earned. Crafting is not for everyone and I understand if you don't want to level it, but as everyone has said you don't have to level them, but if you do I would recommend levelling your DoL with your DoH, it saves you a lot of gil.