The KB 3004394 update ... can cause additional problems on computers that are running Windows 7 Service Pack 1 (SP1) ... This new update is available to remove KB 3004394 from your computer."
Let's not labour this point. 'If it's fixed, don't break it'. If I find at some stage in the future that I'm having problems, like not being able to install updates, I can always remove KB3004394. I cannot penetrate the logic that says if you're having a problem with not being able to install updates, install this update to solve it. This isn't the first time that MS react in this way.
I'll take a small wager that only those with one or more third-party browsers installed have trouble with this update, and that those who don't have trouble are true-blue IE users.