So many factors pushed Ul'Dah as the only town that matters.
1. Central location (Limsa and Grid should have been equidistant to avoid making Ul'Dah the central hub)
2. Central Storyline beyond low levels (Limsa and Grid should have had their own storylines, or at least shared equally in the ones Ul'Dah has the monopoly on)
3. Good layout (Limsa and Grid should not have been so spread out / difficult to navigate in the first place)
4. Non-centralized Market Wards (This would be okay if each community were vibrant in its own right, but since everyone is in Ul'Dah, it actually works against Limsa and Grid)
5. Grand Companies (Again, this works against Limsa and Grid. If certain advantages and rewards are only obtainable through a dominant GC, everyone will flock to Ul'Dah so as not to be left out)
This solution, to make towns easier to navigate, sounds like applying medicine to a dead patient. It won't change a thing now that the damage has been done.
I think more specifically If you're going Aetheryte > Wards, Leve NPC, CityExit, Choco then Uldah is the shortest distance for all.
I like Gridania, but the distance I have to travel when i tele there to any of those 3 is ridiculous.
Otherwise, I think its interesting that (I'm assuming) ALL servers have Uldah as their hub. It could have ended up differently for each server much like the Outside Jeuno flea market was in Rolanberry and Batallia on others. (Batallia was much more sensible ^.^ )