WoW is a huge world where many different factions are constantly vying for superiority. Just because something happens in Northrend does not mean it has to affect Kalimdor or any other continent. Just because it affects a continent doesn't mean it has to affect the entire continent. (Ever see a line of houses torn up by a tornado but one right in the middle is still standing with minimal damage?)
For anyone that has read a lengthy series (I would like to recommend George R R Martin: A Game of Thrones series) you will see what I am talking about when it comes to an intricate plot line that has far reaching consequences in the future but may directly affect absolutely nothing in the here and now.
So I will pose the same question to you that the hillbilly posed to the game warden when they were sitting in the middle of the lake in the hillbilliy's boat:
"Ya goina keep bumpin' yer gums er ya goina fish?"
In other words don't get lost in the details of what may or may not be "quite right", just enjoy the game.