|Merinna on her first Griffon|
The reasons stated are that "flying makes the world feel smaller and less dangerous." Which, truth be told, is entirely an accurate statement. The developers have chafed at a character's ability to simply jump on a flying mount, go kill something that needs killing, and jump on that flying mount to escape the multitudinous ground forces that might get in your way. I presume flying above it all is a way to avoid PvP entanglements on an open PvP server.
So, with those caveats in the previous paragraph clearly written out and agreed to by me, let me state unequivocally that to remove flying as an ongoing feature in the World of Warcraft would be a disgraceful, terrible idea. Removing flying from the game gives way to lazy design by the developers and is disrespectful to the players who have spent years building characters around the flight ability.
Hazzikostas says that it is difficult to design around the convenience of flying. He completely ignores how successfully Blizzard has done this in the past.
Wrath of the Lich King was brilliantly designed for the use of aerial transportation. Many of the zones of that expansion had an impressive verticality that took the ability to fly as a key feature of its exploration. Do you remember the first time you flew into the Storm Peaks, all full of straight inclines and monumentally-sized Titan features? How about Icecrown Citadel, where the ground was so full of enemy Scourge that you had to fly above it to get where you needed to be? How about the Howling Fjord, which, although a starting-level zone for Lich King, gained so much more beauty when you reached max level and could sail through the air jetties of the deep chasms and foothills.