I agree with this and would like to see it stay this way.
While some rare and expensive things do end up on the AH, it is the first place most people go to buy things in FFXI. And if it isn't found there, then they start bazaar hunting. At least bazaar roaming is a lot easier with the wards in this game. :P So finding that prestige piece of gear would take at most, 3 teleports to find what you want if it isn't in the AH. That's not bad for finding a new weapon or gear that you desperately need.
On the flip side, using teleports to find and gather crafting bits or crystals for synth grinding.... not so great. Right now, on our server at least, Ul'dah has become the 'Jeuno' of Eorzea. So it's rather troubling for those of us who don't make our homes there to know that if we can't find it in our city wards we are going to have to make a trip there. And even then, we might end up empty handed, minus a few anima, and with naught but the droning elevator background music of Ul'dah to welcome us.
As for the RMT concern, that will be a concern with any AH type system, as they will always have all day to sit and camp the stalls. There's not really any getting around that unless they simply decide not to put an AH in at all.
To be honest, I'm not sure that's even such a bad idea.
I know the areas already exist for them, but instead of an automated AH, perhaps they could be used for real-time auctions held by players, announced by runners and on these forums with a time/date. I did play a game that had one of these type buildings, with game mechanics assisting both the player selling, and the potential buyers in the audience. I think it would make for fun events and gatherings for those that were inclined to try and get a good deal on something and for those who have mountains of gear piling up that they don't want to just vendor off. The player holding the auction would have to 'rent' the building for the time period which would make up for the listing fee of a normal ah, or the taxes on the wards.
It would take designing a new UI for the seller (for starting the auction, announcing going once/twice, and then sold) and for the buyers (raise bid minimum, double last bid, etc). To make it really shiny, it could even have mannequins or a display table to show the item being bid on. Oh! And they could bring back the auction house music from FF6~