Deafening Crash is absolutely a trait that is very good to have one of, since the Demoralizing Shout extension does not stack, only the damage increase.
I’ve been trying to think of any reasons why Mr Robot would mistanginly value this trait lower than appropiate. The spell itself looks correct in the AMR simulator (with my very limited understanding of it).
One thing that could make it slightly less valuable for Mr Robot is that the standard rotation values thunder clap below a free revenge. This seems unproductive as Thunder Clap does more damage than Revenge, also has a chance to reset Shield Slam, and generates rage.
Especially when tanking many targets (like in mythic+), the amount of free revenges is probably tangible enough to reduce the total amount of thunder claps casted.
If you have Unstoppable force the damage is even larger and you can cast a large number of thunder claps, practically keeping demoralizing shout up for the full duration of avatar which reduces damage for a large amount, and combined with Booming Voice provices a noticable damage output increase.
We could try to make a rotation that prioritizes thunder clap higher in general. I was considering prioritizing thunder clap especially high during Unstoppable Force or Deafening Crash but I doubt it’s worth putting above shield slam or any defensive ability.
Another point is that rather than trying to use demoralizing shout as a rotational ability for damage reduction (and rage/damage output from booming voice), Mr Robots is avoiding to overlap it with any other defensive cooldowns. I don’t know how this affects the uptime however.
Allthough saying all that, I don’t see any major discrepancies that would cause Deafening Crash to be incorrectly valued too low. I might do some experimenting with rotations to see if the number of Thunder Claps is too low or Demoralizing Shout uptime is too low.