I like the market wards since it gives you that feel of having a peddler sell your goods on the street. I did the same thing with my mules back in ffxi, just wished retainers were in a more open place, like maybe open up some doors and windows inside the wards.
The problem is that the market wards have a limited amount of retainers it can fit per ward, and with everybody wanting to be in uldah, that place would fill up quickly and not everybody can have their retainers selling and not have a good experience with the market wards. I feel sorry for those in Gridania.
This will become more of a problem once more people comes in the game and when more people get more retainers. With the mailbox system, who's gonna stop someone from making 8 characters with 16 retainers. A few people can fill up the entire ward with just their retainers and stop others from summoning their retainers. Of course, some smart ass will say, "if you can afford to pay the monthly, it's your right to make as many characters as you want." Yes, you can but once the RMT figures this out, they already have multiple characters each and can obviously afford the monthly once they start charging, they can takeover the entire economy, you'll probably start crying again.
It's not a problem for my current retainers since they are saved in their spot in limsa battlecraft wards, and I practically own the place; but I will feel sorry for ps3 players who can't make money because the wards are so full.
Anyways, here's an idea to make the wards more centralized. Make the search function centralized, meaning it will display items from all cities, and put an aetheryte inside em and allow to teleport to another city for 1 anima or maybe free.