Raid Addon Utility and Changes
Addons that do things like tracking boss timers and better visibility on who is being targeted by what are fine, it is all informational.
Some of the things that addons do that interact with the 3D world such as radars or sending people to specific spots on Mythic Kormrok and Kromog are not great.
You could have much more scripted movement with the current state of addons, micromanaging your raid's movement and telling players exactly where to move in the 3D world.
In Patch 7.1, addons will not be able to access unit position in raids, dungeons, and competitive instances.
The team wanted to get this in Patch 7.0.3, but they didn't want to break some mods that are harmless in the outdoor world, such as the ones that help with gathering or collecting treasures.
Anything that projects an arrow on your screen that interacts with the 3D world or giving you your position relative to others will be broken.
The team didn't want to announce this until they were sure it was doable, but that work has now been done internally.