In rare cases an addon has a negative impact on the game experience.
One I can never remember the name of would plot on the ground the locations players needed to be during an encounter, and would show exactly where aoe would be etc.
That trivalised encounters, and so blizzard found a way to break it.
The other perhaps controversial suggestion would be the likes of AffDots.
That has almost trivialised a gameplay mechanic which can give a pretty significant dps gain.
Blizzard are making changes in WoD to remove much of the snapshotting, and even stated on a blue post that they didn't like how well that addon did in that task.
Unfortunately just breaking the addon wouldn't be feasible.
"Information" tools like meters, gear rankings etc have potential, but tend to be misused by the players.