Personally I don't think we *needed* flying in the old zones. For one they are already small enough traverse in about 1-2min(Besides upper Noscea...) and 2... personally with the addition of flight I'm not gonna see as many people in zones as I cruise around in them because everyone is just gonna be flying high up and make each zone feel even emptier than they were. They could of just added another speed upgrade to move as fast as flying but... probably not because it might be a little uncontrollable. xD
Hmmm... only a few zone are even big enough for flying to matter a bunch (C. Coerthas, S. Thanalan, *E. Shroud....*)