Idk, WoD was a complete mess in a lot of aspects, including the story, but that was due to blizzard's decision to throw WoD under the bus, nothing else. But unlike WoD, this time Blizzard seems to want to carry out the full schedule for BfA, so there isn't (presumably) any cut content that might explain the abysmal writing.
Case in point: Sylvanas burned Teldrassil out of her free will, or she was (is) being manipulated by someone or something else. In the former case, we have Illidan 2.0, i.e. the guy (or girl, this time) who took a lot of frankly !@#$ed up decisions
for the ultimate good In the latter case, we have yet another Warchief who gets a little too high on Old God koolaid and ends plunging the Horde into the second civil war in a decade.
In short we have two very
interesting outcomes: Garrosh 2.0 or Illidan 2.0. That is assuming that writers won't go full retard and pull the Kerrigan card.