Terran used to rely on position a lot where they can't move around the map easily. Now they have their own version of something that can run around the map taking lots of units. Essentially it really is a lazy way to balance the game. If all races have a core unit you can get to somewhat easily, balance won't be broken easily.
It kind of kills some of the uniqueness of the races since terran used to be very immobile and relied on siege tanks to set up positions. SC2, terran just run around with their high hps units and duke it out whenever u see the enemy.