You can built 30 stacks with introspection every 30 seconds (in combat/carnage skill tree). Not to mention that you get them free while fightings.
It takes almost 30 seconds to get from 0 energy to full energy. The biggest difference I can see is right now that valorous call (that builds 30 stacks immeaditely) has 3 minute cd, while cool head has 1 minute cd. However, 0 stacks doesn't affect your fighting in any way, while 0 energy means you can only spam flurry of bolts.
I really think people should stop screaming "give it a cd! It hurts huttball!". This just makes me hate that annoying map even more.
The issue with that though is you go to 0 every death, whereas for a scoundrel, you are back at full energy, so it is a bit different.
I am 100% against giving it a cooldown for scoundrels. I would not support it in any way. I like the ability, I use it a lot on my own scoundrel. My only issue is that I feel it should drop the ball in huttball when it is used.