Now, for tanks in general:
We don't see 'big' numbers very often. The damage we do is small but the threat is bigger.
The idea: While using a addon like SCT, Parrot, MSBT or the Blizzard Floating Combat Text,
do not display the damage but instead display the threat done.
The player has all information for how much threat his attacks are doing.
There are normal attacks that just have to be multiplied by a threat modifier (stance for warrior, etc).
Exceptions are special attacks like heroic strike with an own threat modifier (example: heroic strike).
If you just want bigger numbers go into your favorite combat text mod and multiply the values by ten. lol Big meaningless numbers! As an experienced/geared tank I can't imagine why on earth you would even care about big numbers.
I will take a moment to endorse stat blocks and the TPS block they have developed. It's really an amazingly lightweight and functional addon. Kudos to them.
People are too down on the idea. :)
I think it would be a cool option to have. You wouldn't have to replace the damage done but an option to view Damage (Threat) the same as I can see Healing (Overheal) already would be interesting.