When I say excessive, I don't mean that there are more tank specs compared to DPS specs. I mean terms of the number of raid slots which encounters are designed around.

Most raids these days are filled by 1 main tank, and 1 off tank which most if not all of the time can be filled by a melee dps.

In 10 mans the days of 3 healers are all but gone -- most hardmode guilds bring 1-2 healers per fight. Some extremely rare guilds with VERY high dps are still able to bring 3, but this is a luxury.

Which means if you are keeping track 1 tank, 2 heals, and 7 dps. Which means that when considering the number of classes which are out there, 75% of them have to be DPS specs, 20% heals, and 10% tanks.

25 +5+6 = 36, not 34. By the numbers this means there should actually be 7.2 healers, 3.6 tanks (lets round this to an even 4) and 25.2 dps classes. Which is why I said 6 tanks would be excessive.

You have to remember for every spec/class added to the game there has to be a balance for loot distribution. And while there are many tanks needed for heroic dungeons, there are few if any tank positions needed for raid groups themselves.

Now my numbers might be wrong, but this is how I believe that it breaks down. I am sorry if you took exception to what I said because you have your heart set on the idea of Warlock tanking, but what I said is viable. Down the line -- they may revisit the idea if it makes more sense to do so, but as of right now GC has come out and said this is not their intention, and that their intention is to make this a viable option in some niche situations -- which is more or less what I said.