Agree with the points in the OP.

But i'd add that every city needs some 'real' contents (to play) in each, different from the other ones. Some ideas:

- unique quests with cutscenes, about the ancient lore of that city;

- specific minigames like: dices (uldah), fishing tournaments (limsa), lottery (gridania), etc.;

- an istanced multi-lv dungeon in every city (like the basements in FF11 sandoria). A segment of it could be also used for a battle tutorial. Other segments, for different levels;

- random events (some on specific and recurring dates) for every city like: fairs, musical meetings (in gridania music hall), fireworks, appearing of special merchants or npcs (that gives hidden quests and rewards);

- presence of specific routes, from the city, to reach unique places. Some islands near Limsa, renting little boats from limsa port, for example;

- and when housing will be add, unique house design for every city (with a balcony view of the area).