If Blizz had a similar system for WoD's dungeons, and the first batch of Apexis quests had been less gated and given similar rewards to Tanaan's I think a lot of people complaining about a lack of content might be hailing it as one of the best expansions.
The trouble is Blizz overcompensated for the sentiment that too many things in MoP felt "mandatory," and instead made too much "pointless." It's similar to how they overcompensated for complaints about Cata heroic's difficulty and gave us the snooze-fest of MoP dungeons. On the up-side I think that (as far as quality goes) WoD's heroics hit a sweet-spot, so maybe the rewards scheme and world content of Legion will too.