NO ONE in their right mind would pick a pally or warrior to do heroic runs as tanks. It’s always double DK’s or DK and Feral druid. Dk’s are live lords and bring self healing and magic protection plus a battle res. Feral’s bring a battle res, vate, self healing and 5% to crit. If anything Pally is above a Warrior just for might buff.
I get what you are saying but if we are talking about raid spots and you had to pick 2 out of the 4 tanks who is losing their job?
I have all four tanks at 85 and raided with all of them.
Blood DK feels like 20ilvls ahead of the protection warrior, and 15 ilvls ahead of Prot Paladin in terms of damage taken and threat generation.
I respecced my paladin holy and warrior arms so that they can actually secure raid spots.
Prot pallies are perfectly fine as offtanks in hc raids, as i said before warriors are a bit behind, but even they can do HC. And are even prefered for certain bosses. Blood dk is definitely very good. But you acting as if the others arent viable is just silly.
Also, once again looking at your only 2 hc kills… your groups are literally using prot pallies more than feral, and definitely not stacking blood dks 
As for me personally, i wouldnt really care what tank i have, as long as they know how to play their class i can keep them alive. And honestly, as a healer main. I’d prefer druid/pally tanks over BDK. They are not as good as bdk overall in most cases. But their incoming damage is much more predictable, and in general they are taking less damage overall. So healing anything other than a bdk, while more intensive, is usually a bit less stressful.
Cata was never known for balance. If they couldn’t balance cata back then, and they cant even balance retail, what makes you think they can balance cata classic milky milk?