http://extra-credits.net/episodes/perfect-imbalance/
It is the concept of making a game that has a built-in imbalance.
The reason why I'm posting this is, not only did the video use SC as a prime example, but it sheds light into what Blizz may be doing with the new expansion.
If you don't want to see the video and rather read my boring explanation, here it is:
A good game design incorporates a built-in imbalance which can cause a variety of things, ultimately leading the players and the community to continually form new tactics and bridging the gap between the new players and the hardcore players. A good example of this is LoL, where certain champions may seem to be above average. What happens is that as this champion gets the spotlight, players will find ways to counter this hero, and sooner or later, the counter-champion takes the spotlight. Once that happens, a counter-champion is found to counter the counter-champion, and so the cycle continues. This form of cyclic change in tactics cause the metagame to continually change and never stagnate.
The case with SC and SC2, however, is that the game is so well balanced, that this sort of metagame is hardly seen. Players will often find that certain builds are always the most useful, and the game loses its strategic edge in favor of being able to execute a certain build/action as quickly/efficiently as possible. In other words, one must either be very pro in the game to be able to make new strategies (Such as shuttle-reaver-micro drop) or be really new to the game and still be discovering the new strategies.
This is definitely true in SC1, and I quickly realize this is what, personally, made me lose interest in melee.
On the other hand, SC2's expansions allow Blizzard to unbalance the scale - throw in some crazy long ranged air bomber for the protoss, make zerg anti-artillery, and etc. Before, I feel that Blizzard should have either stuck to the old formula and make things balanced (aka just patch the things that are broken) OR introduce new mechanics that give players new tactics (aka the Swarm Host).
Now, I can kinda see what they're trying to get at. They're trying to create a community in which the metagame continues to change, and honestly, setting SC2 into three expansions actually helps this. I still think a lot of the things are ridiculous and the competitiveness of melee uninviting, so i probably won't get into it any time soon, but I wonder if people are too quick to judge on some of the more "outlandish" balance changes that game developers do in general.
None.