Blizzard makes one of the most balanced competitive multiplayer games out there.
"Blizzard needs to learn how to balance more."


And the new units aren't gimmicks. So far they've all opened up a host of viable new strategies. Will that get whittled down in time as the meta game works itself out? Sure, but I don't think we'll see these new units disappearing from use. Which is what you'd expect to happen if they were just "gimmicks" and didn't actually change the game in new and interesting ways.