Is there some spam protection built in to WoW doing evil things with people running addons without message queueing?
I'm pretty sure there is (or at least used to be - can't see why they would've changed it though), but I can't remember what the timer is set to. I think Sky has some kind of queuer made for this, not sure though.
I've yet to find any raid frame AddOn that can show debuffs I can cure like CTRA does. I play a mage, I keep all 40 people's frames on my screen (I have them set to sit where the party frames are normally and have the party frames hidden when in a raid). Normally the frames are black, but if someone's cursed their entire frame turns a bright red. Oh, I need to cast Remove Curse. Done and done.
The ready checks, the assigned targets, and the encounter notifications (John is the bomb! 5 seconds to AE curse! etc) are also good reasons to use CTRA.
I've seen that debuff thingie in Xraid, but I remember modifying it slightly to include diseases for me (I'm a priest). The name part of somebodys frame turns red for me when they're afflicted with either disease or magic (been thinking about changing disease to some other color, but I'm lazy)