No adons that tell you when to interupt/dodge/block(at least not in pvp), No addons that reveal any kind of info about enemies DPS meters an gear score are a big dealbreaker aswell. The rest is going to come anyway whether i like it or not, ill deal with it.
I'm not sure you really understand the concept of mods OP. Nobody is afraid that they will somehow have addons forced upon them, in fact most of Bethesda's community is "pro-mod" so to speak. The problem is that mods can't always be regulated, and there will always be some acehole who manages to squeeze cheat-like effects into the game. It's too much of a pain for the developers to code in all of the safeguards to prevent wrongdoing. Not to mention that when one user has a mod, others need the same mod to see it on their end. Mods just aren't friendly for a large scale MMO.
Please use the existing topic about: http://www.gamesas.com/topic/1490509-add-ons-and-pvp-merged-similar-topics/