@Edhel-dur
So, you wanted a "good" WoW story? By your own principles, this means that the outcome must be unpredictable, and that there's no definite good guy vs bad guy, yes? I'll start out by saying that the main plot of RoC certainly doesn't follow this definition. There, we have the united forces of Azeroth standing against the big bag Burning Legion, who, in the end, are defeated (who would have guessed, right?). Of course, this is just one of many plots in the game, and, as you've mentioned yourself, TFT very much moves away from this black and white portrayal of the world. Another thing worth mentioning is the difference of the story element in the two genres. While the story plays the central role in the RTS genre, the MMORPG has to have other just as important elements for it to be succesful.
As for the WoW story. Personally, I was very intrigued by how they made Garrosh's story. To begin with he's this lost son of Grom, who's been living with the shame of his father drinking the blood of Mannoroth. Now, as the player (and eventually Thrall) encounters him, he learns that Grom ended up freeing the Orcish race from the demons. After this he goes to war in Northrend, and eventually becomes the Warchief and so on. Garrosh is initially portrayed as being hot-headed, agressive, and somewhat racist. He also brings the war with the Alliance to a whole new level. This is when things start to get interesting. In the Stonetalon Mountains (Cata edition, of course), Garrosh is shown to develop more sympathic traits, and it is hinted that Garrosh's story would eventually lead to redemption. This, however, is not at all what happens. Garrosh starts to lose his grip more and more, and actually ends up doing exactly what he was opposing in Stonetalon (dropping a giant bomb, that is). In the upcoming WoW patch, Garrosh is going to be the final raid boss, and even his own Horde has to fight him.
Note that I am in no way saying that the story in WoW is even close to being as good as the one in WC3. However, I do think it's better than what you give it credit for.