I'm going to just say it: Jewelcrafting is a failure. At first the idea seemed sound: use sockets to make up for low stats that benefit from hitting a cap, such as hit or expertise. Somehow we ended up with plenty on gear, to the point that at many times I found myself well over the hit cap but with no options for other gear pieces. But even when not, only a few gems were sufficient to hit the caps. This left plenty of sockets empty, waiting for me to gem one stat and only one stat. Bonuses were usually too weak to be worth using hybrid gems.
In the end jewelcrafting did help a bit with gearing issues, but the greatest effect was to drive ore prices through the roof and shift loads of gold to jewelcrafters. No longer was new gear better, since without the sockets it was usually weaker than the previous piece with sockets, so upgrades were left sitting in bags until the player could go to a city and drop hundreds of gold on new gems. This wasn't fun for me and I doubt anyone actually enjoyed it. I'm also sure I'm not the only person who was mildly annoyed after loot handouts to immediately hear "anyone here a JC?"
With ore prices so high, farming was better than ever. For gold sellers. Add on top of this a ridiculous glyph system to drive herb prices and it's no wonder botting was completely out of control. Of course in the case of glyphs it didn't help that the markets seemed to be dominated by those with the least scruples and therefore greatest willingness to deal with illicit herbs.
First off, it's not as simple as jewelcrafting. You won't always get the same stats for every piece. You have to think about it a bit. Or get an addon to add up everything and tell you the perfect combination. But at least it's something more than just stacking the one best stat. You can't even do that with reforging since the best stat might already be on the gear, so you want to go for the second best.
This isn't all of why I like it.
I like that it's flexible. And by flexible I mean cheap. Can you imagine if regemming an item only cost one or two dozen gold? Wouldn't you be more inclined to get every stat perfected? Wouldn't you be more eager to get upgrades if fine-tuning them didn't cost you a day of dailies?
I think we're going to see a new divide. Previously I was the sort of person who would get new gear and see I was over or under this or that cap and think "fuck that" to a 200g gem just to tweak one stat slightly. I still am that person, but now I can tweak stats without spending 200g on a gem. Or perhaps multiple gems for thousands of gold. The gold excuse for poor stat structure is going to be a lot weaker. While I'm certain that gear costs will go up and reforging costs with them, that's the usual expansion inflation, so it will be chased by coin drops, daily rewards, and vendor trash.
I think we're also going to see more players just playing better. You see, people are irrational. All of us. But all in different ways. Some people are irrational in this way: if the consequences of information are too expensive, they avoid the information. In other words, if the problem is too expensive to solve, they'll pretend there is no problem (sound familiar in politics?) Someone who cannot afford to implement general knowledge of their class mechanics and stat preferences can avoid cognitive dissonance (I'm a good player : my gems are all wrong) by not knowing that their stats are wrong. Make it cheap to fix the problem and people will be more willing to accept the existence of it.
With people less inclined to buy expensive gems to fix a few stats here and there, we'll see demand go down, and prices along with. Of course there will still be new gems for new gear and that will keep up prices, but they'll still be lower, especially when considering that those most inclined to regem for small DPS gains are also going to be more likely to pay anything, meaning they're holding up the high end of the market. Gems will be similar to glyphs, which of course are high now, since we're all rushing to buy our ten dozen glyphs per class. But after that, vanishing powder. A new spec no longer means hundreds on new glyphs; a buff from Blizzard, a nerf from Blizzard, a new piece of gear that shifts the rotation; no longer will we need to run out and buy new glyphs. A simple powder will do the trick. I doubt it will be dirt cheap, but less than current glyphs? Definitely, especially since making one market out of hundreds means greater competition and lower prices.
I got a new tanking weapon, so I'll have to go reforge some of my gear to fix up my expertise. I'm looking forward to it.