To balance or to imbalance.

So lately I have been reading a lot about balance in games, both academical and non-academical. And many gamers in multiplayer games seems to be arguing that their games are not in balance, and that some champions (League of Legend/Dota 2) or class (most mmos) are more powerful than others. But why is it that game designers are making these imbalanced choices or mechanics?
Well if you look at games without balance such as Chess or Starcraft, these games comes down to execution and strategy, and in Starcrafts case speed aswell. Players have a symmetrical chance of winning the game.
But by adding an imbalance to a game, some players will switch to that strong champion (LoL/Dota) to win, that will in effect cause the remaining community to develop strategies to counter the first imbalanced champion. The strategy might be the use of another champion to counter or a combo of more, then that strategy will become dominant until it is countered.
The effect of the imbalance is then that the game is never stale, and it keeps players experimenting with the game. While games such as the fore mentioned Chess and Starcraft have predetermined strategies, while the games are a bit more stale in my point of view, they can take years to master and have a very high skillcap. Chess can take a lifetime to master, and even then you might find yourself beaten.
Whether or not a game is balanced, it really is a fine line to control balance in computer games.