I don't think it could harm the economy either. If nothing else, an AH linked to every city will help crafters who don't spend their time in the economic center of their server. On Besaid it's Ul'dah. Ul'dah wards are packed to overcrowding, whereas Gridania wards are pretty much deserted and Limsa is somewhere in between.

Still, though most gear and some odds and ends for crafting are a huge pain to find because of this, I'm pretty much on the fence as to whether they actually need to add an AH right now. If they do, it can only help, as far as I'm concerned.