I guess the following hints which they released at Blizzcon weren't enough for you:
1) The expansion is about stopping the Iron Horde.
2) Tanaan Jungle is the seat of power for the Iron Horde.
3) Only part of Tanaan Jungle is used for levelling, the rest is for L100
4) Parts of Draenor will be unlocked as the expansion progresses, like in Krasarang Wilds and the time-gated questlines such as Isle of Thunder
Perhaps you weren't able to join the dots, but I don't think many people are actually surprised or even bothered, since it's something they've done regularly over the past few expansions.