Consider two competing possible design alternatives for how tanking a boss with Intimidate could work.
Option 1
"A high Intimidate skill lets me hold aggro on this boss, despite doing zero damage. I will hold shift to shield-block and click Intimidate every 10 seconds until someone kills the boss for me."
Option 2
"A high Initimidate lets my attacks hold aggro on this boss, despite doing under half the damage of some teammates. I will press shift to shield-block whenever I see an especially dangerous situation, such as:
* the boss winding up a special attack
* an extra monster attacking me
* the healer being distracted
* my AC buff wearing off
* getting a healing-immunity curse
* or simply me having low hitpoints.
At other times I will attack the boss, both to help win faster and as a necessary part of holding aggro, because Intimidate by itself isn't enough."
Which of those two designs would lead to a game that's more fun to play?