I think it's also a tanking problem in your case and the tank didn't generate enough hate.

However, what's true is that monk and samurai are the only dps to have 1 way to reduce hate.
Caster have both diversion and lucid dreaming.
Bard/Mch have MP/TP regen, with the secondary effect to reduce hate.
And like you said, Ninja and drg have their own.

It's always great to have another option to reduce hate when diversion is not ready, especially if you're generating too much or if the main tank dies and the other has to build hate quickly.