Who knows. Most creative folk tend to have huge ego's and aren't very receptive to criticism...especially when you've got the clout they do. I don't know Metzen or any of the creative staff at Blizzard, and I'm really just generalizing here based on my own personal experience.
It's easy to listen to and react to user feedback on balance decisions of the game because it's something tangible which can be measured. But creative elements like unit design or lore are so subjective.