So for you, using TBN during a TB or to protect a heal in pain or the other tank is useless? Making dps is good, but if you are tank, your first role is to make the team survive.
This is the kind a words that irritate the dev team: "dps dps dps dps dps..." and that's why they've made mob more powerfull and tank less powerfull.
Again, if you've the luck to raid with 7 other players with you are in symbiosis, it's not everyone's case, and as a DRK, I never hesitate to put a TBN on the other tank or another player in trouble.
If they die, then you'll have a bigger dps lost than using a TBN.
And you can't affirm they'll make Shake it off a support utility, and if they keep the same eye on the idea to make the team works together instead of just dps, WAR has a chance to be out.