Tank DPS started to matter as soon as blizz made tnaks do compettive dps and tuned fights with that in mind!
Sorry but I don't see tank dps being a "secondary not important" part of tanking when one can do this:
http://www.worldoflogs.com/reports/d...?s=1888&e=2261
And I don't knwo how you can manage to do that if you are clicking!
As well active mitigation > your tanks can miss buttons all they do it keep threat comment.... I mean are we even playing the same game? have you even tried tanking in mop?
and again this if for normal modes... I would only assume heroics emphasize this even more!