Starcraft, Starcraft 2 and Warcraft 3 are not symmetric, but still so balanced, that it became a sport in korea...
And this nearly perfect balance has allowed SC to live for more than 10 years in a scene, that is usually fast living.
Symmetrie is nice (Warcraft 1 and 2 are relatively symmetric), but achieving balance in an unsymmetric game is a lot more interesting.
Wesnoth, a free game also achieves quite good balance with 6 very different races...
the only thing that you have to remember: map design is important... some kind of maps outright favour certain races (in sc2 or wesnoth)
For D&D it is adventure design, and to a lesser extend map design... but still, a map with nowhere to charge makes charge builds obsolete... a certain skill challenge already makes some characters not beeing able to do a lot...
So in the end, when a computer game has to achive balance for all, in every possible scenario, an RPG can spreadits balance around a bit more, as the DM is (usually) more adaptible...
Problematic are situations, and that is clearly stated in mearls' article, when someone takes or at least tries to take all spotlight... which is not bad per default, but when he is actually more able in all these things, than anyoone in the party, most players start getting annoyed...
This is one of the major complains of 3.x... something i don´really share... if you don´t have 5 min workdays, and not every possible feat or magic item, the relation between fighter, mage, cleric and rogue is not so imbalanced...