It's funny seeing how Blizzard initially wanted to give deep back stories to the player but realized it was a bad idea as it would give every player the same story, and now every expansion is "Champion bringer of Maw Walking and Hero please kill some boars."
It's like they forgot people join the game at different points and some people will be veterans while others will be newbies. They have these weird things called achievements that they could tie story into on a purely superficial level, but decide not to.