Even right now, all of those nice fire patches on the ground won't help you that much to do "max dps" (enough to cheeze by people in WoL but not enough to push you from doing half of dps dmg to 1.5 dps dmg).
Granted i don't have a problem with tanks not getting veng from standing in void zones and fire patches.
But nerfing tank veng gained that they get from legitimate tanking is silly.
And there is no floor, i've seen tanks doing ~50-60k dps in heroics with veng. It's not just a magical +100k dps buff.
And let's say we do nerf tank damage, what's next ?
Tanks complain about healers doing any damage what so ever "shut up and heal"
And we go back to wonderful world where dps do normal dmg, tanks do invisible damage for threat and healers just heal. Great, sounds like fun game.