I disagree. Blizzard doesn't seem to be about gameplay, I find that they focus on balance. Take a look at SC2. Nothing's really evolved. It's been polished, polished until it gleams, but it's not evolving the gameplay experience.
If SC2 wanted gameplay, they could have done some things better, like not limiting the zoom levels and allowing for better smart commands like modifying waypoints on the fly. Take Supreme Commander, that's pushing gameplay, but the balance was off.