To those that said "Vent is essential":
Get a fkin clue. We went from pugging Kara to horde first MH/BT attunement to horde first on most bosses in there to server first Brut without the use of Vent or any other form of voice communication. It was a spanking new server so we were months late on raiding, reason why we only got up to Brut pre 3.0.
Vent is NOT essential. Good communication skill is. (and mature players ofc)
DBM isn't essential either. Raided weeks without it and didn't miss it one bit. All it does is clutter your chatbox.
Pre 3.0 I would've said Omen for sure, but these days even that isn't needed. Unless you have sucky tanks. (Although I managed to score 8.2k tps with BL and blowing CD's and super lucky crit streak, it ended in me dying, but was worth a lol)
So in answer to the OP, no, you don't need any addons with the current state of the game. Common sense should suffice.