Builds are tight and I tend to drop things in a finalized level 50 build due to not having as much use as say a defense/resist/lotg IO mule.
In the event of my fire/dark controller I just had no room for a 4 minute recharge aoe hold power when I had so many other things to do like setting up Darkest Night+Smoke or throwing down dark pit+dmg slotted bonfire meanwhile setting up hot feet containment with cages or teleport targetting my servant into melee to floor enemy tohit down to 5%.
The point I am trying to make is there are higher priorities (animation time, recharge time, powerselect/enhancement slots). and this happens a lot to me.
And back to the variable thing from before, I tend to play on 8 person teams when leveling up. Only using aoe holds once or twice a mission due to their recharge times when I have so many other options available... i skip.