I don't see how this does a better job at increasing security beyond the built in anti-malware/phishing stuff in Firefox.

Sure, you might have more people reporting stuff but you don't have credentials for any of those people. If they went to 20 sites in the last hour and now have some malware, are all of them going to make the correct decision on which of the sites it came from?

After reading this from the privacy page:

=====================================================

Background information such as age or gender is used to provide statistical information about website preferences. This statistical information is stored without any personal information.

=====================================================

I think that someone might be selling website demographic data...

I can't think of any other reason why you'd write a Firefox extension that competes with a built in feature of Firefox, especially when the data coming in isn't vetted in any way.