I feel having bigger area's that you'll just zoom through (high above in the air) will definitely hurt the quality of the designs.
Not just because of the extra work they have to do for larger area's, but mostly since for them there is simply no point to it if people can fly through it quickly. It would be a real shame, since for me the real magic of Final Fantasy XIV is in the crazy details they put in every little step you take through the world.
____________________________
[XI] Surivere of Valefor
[XIV] Sir Surian Bedivere of Behemoth
http://na.finalfantasyxiv.com/lodestone/character/2401553/