While many people don't realize this, the question of crafting is actually a really big issue for developers from inception all the way through content. There are so many variables to consider, that it can change radically with just simple decisions.
So, how do YOU think it should go?
Some things to consider:
1. Will it be based off self-farmed materials, materials available on the AH, materials available from vendors or something else (feel free to offer your own ideas).
2. What crafts will exist? Or, rather, what kind of items should be available for crafting (so that you don't need to get specific like Tailoring and Leatherworking)? Will all weapon and armor varieties be represented? Will any? Will the items be usable only for yourself, for others, or some combination? How about consumables? Will they be offensive, defensive, buffs, debuffs or just for fun (food vs. fireworks).
3. How intensive will that aspect of the game be? Should a player easily spend most of their time crafting and playing the AH, like in FFXI, without things getting too boring? Should there be a chance for failure and high quality items? Or, should it go the "WoW" route and have no chance of failure and no chance of high quality results, with the craft times taking 10-30 seconds and, basically, having readily obtainable items (most can at least be bought, even if they drop in difficult end-game dungeons).
4. How many crafts can you raise to max? How many can you have? Will there be "primary" skills (like, in XI or WoW, the main crafts you can raise to max) and "secondary" ones (fishing in both games, plus two others in WoW)? Should a single character be able to be a master smith, tailor, alchemist and fisherman if they want to?
5. Do you want some craftable items (granted, with mats that aren't easy to get or cheap) to be comparable (and maybe even better) than endgame dungeon items?
6. Do you want crafts to offer passive bonuses (like a miner having higher strength from always swinging his pickaxe, a tailor having higher dexterity, etc.)? How about active ones (like a smith being able to imbue his weapon to inflict fire damage for 30 seconds)? Should different jobs get different abilities (fire damage on spells instead of weapons for a Blm)?
What are your ideas?