As an example Fate shares with the readers an experimental talent tree for Wrath (and a very nice job, I should say), and references this as just one very complicated aspect of the design of the game. Analyzing every angle of a spec may go very well, until you open it up to the players and realize what you thought was balanced really is no where close. Things go from bad to worse, and the players begin to complain, and complain, and then they, you know, complain. Trying to keep everyone happy is really a thankless job, and this is only one tiny aspect of the game. It doesn't take into account building boss battles, creating loot tables, designing armor and weapons, or anything else that makes this Massively Multiplayer game so very massive.
I haven't considered exactly how much work really goes into building this game, keeping it running, pushing through new content and keeping it balanced at the same time as not completely ruining the old content. Fate has put it all into perspective for me. Although I'm not much of a ranter or a railer when it comes to the Blizzard devs, I certainly from this point on will give them the benefit of the doubt.