Sure it has been taken away. You get it back at the end of the expac, playing some content you wouldnt play otherwise.. as like luring everyone into exploring everything, and as like playing some dull grind quests as like in WoD.
Actually, your idea is hypocrisy. "It isnt removed as its available when the expac is over"..
So, expect the fact we probably will get another one and a half content drought after legion, we exactly wont have flying while the most interesting phase in playing the game. You will get it after "Game over".
Sure, it is great to continue to play civilization after you had victory.. but it's not the same, what do you think?
You get a reward which allows you to see everything after you saw everything.