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.
I have six third-party browsers installed, but all I had a problem with is Virtualbox not being able to load any of my VM's. I was also able to remove the specific KB3004394 update easily through the control panel's "view installed updates" screen (this was the morning after, so long before the uninstaller-update was released), and after a reboot all was as it was before.
I have not done the "uninstaller-update" because, indeed, if it's fixed, don't break it :) So can't say much about that.