With all the QQ about people hoping that ICC is not puggable, and that it is a challenge, how about making achievements for having no addons enabled. Pretty easy for Blizzard to implement as they already have the coding to disable certain addons.
I suspect even the uber guilds would find life without addons pretty challenging. Any boss kills could be put down to the skill of the people killing them rather than partly down to the co-ordination tools that a kind 3rd party programmer has given them.
On the other hand, maybe the reduced lag would make things easier... /sarcasm