Because spanning all the servers allows the Trading Post to provide a very efficient market, it's been subject to some heavy criticism from MMO bloggers.
While not criticizing the Trading Post, Spinks notes that:
...raw materials (particularly metal, cloth, and leather) typically sell for more than the finished pieces.
How is this new? This was always the case with WoW items crafted from trainer recipes. The issue is the crafting system, not the TP. (I don't mean to imply that Spinks is a wannabe monopolist; I just wanted to point out that selling crafted items below cost is not new with GW2).
Tobold weighs in with a piece titled Crafting regrets in which he says:
I think Guild Wars 2 is extremely bad for making money from crafting, because the auction house spans all servers. There is no opportunity for arbitrage in such a large economy. [my emphasis]
There simply doesn't appear to be a point to crafting in Guild Wars 2. Are the any "bind on pickup" recipes like in World of Warcraft? If not, I'll just buy everything for cheap on the AH. [my emphasis]
Arbitrage—that's something Wall Streeters do. I've done it to earn gold in MMOs, but I've always felt a bit dirty doing it. I think it's excellent that the efficiency of the Trading Post reduces the opportunity for arbitrage.
I read Tobold's post a few days ago but had forgotten it by the time I read and commented on Elder Game's The Case Against Auction Houses. I'm reproducing my comment here in full since it serves as an excellent rebuttal to Tobold's desire for monopolies via bind-on-pickup recipes. On Elder Game I wrote:
I love crafting, particularly to make items for my main and alts.
Sure, it's nice to be able to sell at a profit, but not if it involves monopolies. What the crafters who whine about profit are really saying is "I want a monopoly." Personally, I wouldn't cater to the wannabe 1-percenters, but hey, it's your game.
In-game shops use geography to achieve local monopolies (perhaps shared with a few others). Not all locations are as good as others, so how would the game decide which players get to have shops in the prime locations of the crowded main city?
The problem isn't with the AH, the problem is with crafting systems. WoW limited the supply of crafted items by making some ingredients rare, but mostly by making recipes random rare drops; anyone lucky enough to get a Pattern: Rich Purple Silk Shirt can make a bundle, either by selling it outright or as a tailor making the shirts.
Worst were the bind-on-pickup recipes that dropped in endgame instances so that non-raiders had no hope of ever acquiring them. As someone more interested in crafting than raiding it was one of the things about WoW I hated most.
The issue is how to limit the supply of crafted items in a fair and equitable manner without resorting to using the random number generator to award monopolies to 1-percenters.
As I see it the problem is with designs that make it possible to create items in the blink of an eye. Why do so many games allow one to "lovingly handcraft" a valuable item in the time it takes to click a mouse? Craftsmanship implies labor over a period of time.
One game I've seen which implemented a crafting bottleneck well was Fallen Earth, where crafting takes real time whether you're playing or logged off. Making crafting use real time limits the supply without resorting to randomness or monopolies. Yes, it's still open to exploitation, or at least mass production, through the use of alts and additional accounts, but the idea of making item creation take real time seems like a good mechanic.
It leaves unsolved the issue of how to provide a sink for all the commodities left unused by a time-throttled crafting mechanic.
There are other ways to improve the profitability of crafting instead of implementing recipe monopolies or making the Trading Post less efficient:
First, others in the thread brought up the old idea of real wear and tear so that items don't last forever but wear out and require replacement.
Second, eliminate gear as quest rewards, and do away with 99 percent of all item drops from mobs so that they only drop salvage items or vendor junk. A useable item of any quality dropping from a mob should be a rare thing. Make the majority of gear in the game player-crafted, except for a handful of items.
The ancient trope of phat lewtz drops carried down from the pencil and paper days of Dungeons and Dragons hurts crafting more than any Auction House. Early D&D's focus on combat at the expense of crafting has persisted in RPGs for years and continues in MMOs.
For the first couple of years of its existence, Minecraft had it right in that mobs only dropped raw materials. I was very disappointed when an update cause mobs to sometimes drop weapons and armor, possibly enchanted.
As I see it, Guild Wars 2's changes to crafting and commerce aren't the problem—the real problem is that the changes didn't go far enough.