I can't believe there are so many comments on this topic when the video clearly states that flying is only disabled until Patch 6.1.. Disabling it for the whole for expansion is ridiculous. The great thing about allowing flying in the Eastern Kingdoms and Kalimdor was re-designing the zones so that the landscape properly blended with each other, and that we could actually access these higher up parts of buildings because they were essentially an illusion before then.
If Draenor wasn't designed to have flying mounts, then the designers would take more liberties. Oh, and they won't remove flying/flying mounts so late in the game. They have just as many advantages and disadvantages. They should be used sparingly. We don't need another thread about flying unless it's something worth commenting on.