When Lead Developer Ghostcrawler was fielding questions from Death Knights concerning the viability of dual wielding, he made an interesting statement:
Part of our goal with the death knight was not to have a tanking or PvP tree, and we feel we’ve been pretty successful with that. However, adding dual-wield to that matrix just gives us an impossible task, because then you need to have the Blood dual-wield tank spec and the Frost two-hander PvP spec and so on. We think in this case our only option is to remove some player choice in order to provide a real choice in other areas.
Death Knights already have more options to balance than any class. They have 6 possible specs whereas all other classes have only 3. Adding Dual wield options to every Death Knight spec would give 12 possible specs.
It does make me wonder where the line is for the impossible matrix. How many specs are too many balance.
If you remember back to early incarnations of WoW, each class had a spec for a certain area of game. Think back to early Warriors. Prot was your Tanking tree, Arms was the PVP tree, and Fury the PVE DPS tree. There were no Death Knights, so WoW had only 9 classes. That gave you 9 DPS specs, 9 PVP specs, 4 healing specs and 2 tank specs to balance. Now fast forward to WotLK. The Developers decided to add a class, but not only add 3 more specs. They decided that Death Knights should tank and DPS in every tree giving 3 more DPS specs and 3 more tank specs. At the same time they decided to finally bring Paladin Tanks up to par.
So in Wrath the design would have become 12 DPS specs, 12 DPS specs, 4 healing specs and 4 tank specs. But the Developers were really feeling their oats. They decided that every spec should be usable in every area of the game.
Suddenly, you have 22 possible DPS specs, 30 PVP specs, along with still having 4 tanks and 4 healers. Balance becomes much trickier.
So the question becomes at what point do you reach the 'impossible task'? Would the game be better by limiting the number of specs that were viable in each area of the game. This is someting that truly couldn't be changed until an Expansion, but it would seem self evident that even 12 PVP specs would be easier to balance than 30.
By removing some player choice the developers could provide a real choice in other areas?