What made jewelcrafting such a richly designed profession? First, the profession had an indirect gathering method. This kept the levelling field somewhat random, forcing you to choose your best path for progress over and over. Second doing a daily quest was a key portion of levelling jewelcrafting and learning your recipes. Third, the high level of customization of jewelcrafting profession-rewards gave jewelcrafters a lot of interesting choices.
The indirect method of gathering jewelcrafting materials is worth mentioning. The issue here is that you can't just go out into the world and farm gems. Instead, you have to farm metal ore (or have someone farm it for you), and then you prospect that ore. Each time you prospect a stack of ore, you receive a random smattering of gems. Sure, the quality of gems change according to the metal type, but the color of gems you receive is random.
Why does that matter? It means you can't simply decide to do a little bit of farming and hope to get the exact materials you need. You can grab raw gems from the auction house, but those were rare and expensive at the beginning of the expansion. Anyone who wanted to level jewelcrafting needed those gems, and since the only people who can prospect are jewelcrafters, there weren't a lot of spares out there to be had. So, you were constantly learning the recipes for the gems you had, as opposed to farming the gems for the recipes you know.
Oh, sure, there's lot of jewelcrafting recipes. But that's the point. By virtue of constantly getting somewhat random levelling materials, you're "forced" to cycle through more recipes than the bare minimum to get by. You're constantly poking around in the different jewelcrafting categories.
In my experience, the random gems then make their way into guild banks and the auction house. It makes the tableau of available gems wider and more diverse than you would see if you could just level by firing through two hundred Bloodstones.
Dalaran Jewelcrafer's Token
Zach had an interesting article about the problem with Dalaran Jewelcrafter's Tokens back in December 2008. The issue with Dalaran Jewelcrafter's Tokens is that they're used to purchase any end-game recipes utilized by the jewelcrafter. And they're earned by completing the jewelcrafting daily by Timothy Jones.
The good news first. Jewelcrafters get their own random daily. It's a fairly easy daily. You go out into the world to find a creature type (revenant, vrykul, iron dwarf), and kill a handful of the critters until they drop the quest item. It really doesn't take long for the item to drop. The down side is that you do have to go out into the world to do that, and it usually takes you somewhat out of your way. It's not a big deal, the daily only takes about ten to fifteen minutes. Of course, by the time you've done it your 300th time, you might be a bit tired of the quests.
Dalaran Jewelcrafter's Tokens are the lifeblood of the profession. Your endgame recipes and your profession-specific gems both demand you spend between 1 to 4 tokens per item. It takes freaking forever to learn all the gem recipes.
Of course, that was a little bit on purpose. Blizzard wants players to rely on one another in order to get your gear fully gemmed. But if you're the kind of player who wants to complete their recipe list, this requirement can feel like one heck of a burden.
And not to play the grass-is-greener card, but jewelcrafting is the only profession that's gated this way. You had to log in every day, or else you missed your chance at doing your daily. Everyone else who spends tokens to learn recipes could, in theory, keep farming until they had enough tokens. Jewelcrafters had to log in every day.
That "every day" requirement wouldn't have been so bad if you didn't plain miss out every time you missed a day. If I had a busy week at work, and didn't get much play time until the weekend, I could have missed out on 5 tokens -- and there's no way to get that missed opportunity back.
If the designers re-use this daily-quest method in Cataclysm, I hope that they allow you to "store" your dailies. That way, if I did miss all week, I could catch up and run 5 on Saturday. I don't actually mind the gating aside from the missed opportunity issue.
Flexible Profession Bonus
We've talked a lot about profession specific bonuses before. Jewelcrafting not only gives a character stat-bonus like all the other professions, but that bonus is also incredibly flexible. Most of the profession bonuses are limited to about 80 attack power, 47 Spell Power, or about 60 Stamina. There's a few professions that have a different-but-equal bonus, but they all tend to be worth about the same.
Jewelcrafting, however, not only provides that character bonus, but also lets you customize it in nearly anyway you wish. Would you rather have Haste or Armor Penetration than Attack Power? Jewelcrafting can get that done for you. The jewelcrafter-only gem (Dragon's Eye) has all the same variety as regular gems, but with the additional juice of a profession bonus.
I actually think this should be nerfed a tad in Cataclysm. Or, even better, this level of customization should be shared with more of the other professions. The idea that jewelcrafting was considered the go-to profession for so many raid-roles in Wrath of the Lich King was kind of a bummer. Since professions are such a "genre" role for characters, making it such a no-brainer choice killed many of the other professions for a long time.
(As a note, Blacksmithing shared this customizability, since their profession bonus is a couple extra gem sockets.
So, in summary, there are three basic things about jewelcrafting I'm hoping for in Cataclysm. First, I hope the indirect gathering method is carried over into the new expansion. It made the craft interesting in Wrath, and I think it will do the same in Cataclysm. I do hope that the gating method, if continued, is handled in a way that players don't "miss out" by not logging in every day. Lastly, I hope the incredible flexibility of jewelcrafting is shared with the other professions, so that fewer players feel shoehorned into this craft.