Have you guys never played this game? This was a part of every expansion since flying was introduced outside of BC (where you could only fly in Outland)
You still can't fly in Wintergrasp when it's active.
You still can't fly in Tol Barad ever.
You still can't fly on any of the isles (Thunder, Giants, Timeless) in MoP ever.
Tanaan Jungle was the first "Awesome Isle Content" you could fly in and that was likely only because they realized that WoD was a shit sandwich and the only way to keep subs was to let people fly wherever the fuck they wanted.
I was very surprised when they allowed it on the Broken Shore.