I think that's just it. Blizzard rarely lets the narrative guide character development. It's whatever character that an external source deems relevant that receives attention, whether or not they actually require attention or if their involvement makes narrative sense. Pushing Sylvanas for the past three expansions in symptomatic of this.
Sometimes a character's entire previous characterization is thrown out the window because someone decided to shoehorn them in, like Deathwing himself and Zaela of the Dragonmaw Clan.