Very simple. EVE.
I want this to be like EVE. With an EVE-like interface. And all the data-mining trimmings.
Not just because "I wanna", but because these censored double-censored triple-censored but a dog and a deranged macaque are involved fine game designers at ZOS took the first baby step in that direction - tying each item listing to a specific physical location in the world - and then stopped. Resulting in a stupefyingly non-user friendly system, not helped by the cross-platform aspect (i.e. no "word search" box because consoles).
EVE shows you how tying items to physical locations can still work beautifully, and it starts with the interface, which, among many, many other things, lets you browse and trade all listings for a given item across the entire sector (somewhat modified by trading skills if you are a seller), though you still have to go to the physical location to pick up your purchases. [Which is the right way to do physical location systems, in my opinion, whereas ESO has it precisely backwards.] Not to mention the seamless incorporation of TTC and MM-type functionality (and more besides) without any add-ons.
Of course, this isn't going to happen, because ponies. Actually, because it would completely revamp the current trading guild system, where you sink in-game gold to bid (weekly!) for prime retail locations (where your listings might actually be seen). In fact, this is a much deeper issue if you think about it - the only way that the gold-sink bidding-for-prime-locations works is if you have substantial information assymetry, i.e. cannot see all the listings at once. So what ZOS really needs to do is think about how to restructure the trading guild system from the ground up - for example, adapt a monthly "corporation fee" system from EVE (but somehow tiered or scalable to prevent the largest guilds from becoming gazillionaires), play around with tiered commissions/sales taxes, introduce some other thing for high-end guilds to sink their profits into. Then you can start layering in a global view, whether a classic auction system (LOTRO, TOR, many others), or some *** child of EVE, or...I actually do not know of very many other ways of doing it, because most people did not go the ZOS route and did not try to reinvent-the-bicycle-because-ponies.
Rant mode - disengaged.
(...)
EVE shows you how tying items to physical locations can still work beautifully, and it starts with the interface, which, among many, many other things, lets you browse and trade all listings for a given item across the entire sector (somewhat modified by trading skills if you are a seller), though you still have to go to the physical location to pick up your purchases. (...)
I'm kinda torn.
There are people for whom the economic game is interesting. I used to be one of these people (I no longer am, though), and I've met a lot of people like this. These are the kinds of people who would play games in the economic simulation genre. A central auction house is very utilitarian, which is good for people who just want to buy or sell something and be done with it. But it's boring and doesn't offer any sort of play for people who like economic games.
So it comes down to your mindset. Is in-game trading just a tool to help you get what you want? Or is it more than that--a game in and of itself to be played? As someone who used to fall in that category and who knows many people who do, I appreciate that depth that the guild trader system adds, even if it comes at the cost of convenience for people who just want to get a transaction done and over with.
On the other hand, I am a trade guild GM, and running a trade guild is stressful--I know a number of trade guild GMs who have stepped down or even left the game entirely because of it. And I dread Sunday nights. So a part of me wants to see the system abolished. Or at least reworked so that it can retain the flavor, but without the punishing stress of the current bidding system.