This is basically what I'm getting at. You can't rely on a tank too soak up damage if you have no way of forcing the enemy to attack the tank. Unless you're doing a solo character run, you have to count on your other party members getting damaged instead.
More importantly, offense abilities have the benefit of always being used because you're in control of what your character does vs defense abilities where you can only react to what the enemy does with no reliability of whether your ability will be used against them.
Basically, because you can't control who the enemy attacks, defense abilities need to be stronger to compensate for that factor of unpredictability.
