Your comments

The problem is pretty clear, it seems. Not much to check, no? And advising users to open their browsers to all kinds of exploits via unscreened addons is surely not a practical solution. 

That "solution" sounds like a terrible idea for security purposes.

Me too - they didn't give any warning and just dumped the addon. It still works in Chrome (but for how much longer). Browser hijacking isn't being looked upon fondly by the developers.