Come on we can't have it both way : promote the standard based Web and complain about the death of 3rd party plugin !
Don't get me wrong, my beloved firefox is not better. It wants me to install dev edition to be able to install anything.
We made a mistake somewhere along the way.
The modern browser 1. is its own OS, but 2. doesn't have any concept of a privilege-level separation. That means any random program running as user X is free to install an extension into user X's Chrome or Firefox profile without needing to ask permission. And then said extension can harvest your social-network profiles, replace ads with their own, etc.
Modern operating systems have a concept of users, groups of users and dedicating one of these to the role of administrator. I see no problem in not enforcing signing rule for the extensions installed by administrator (at system-wide locations, not user profile) - they are read only for the rest of the users anyway, so they couldn't be installed by drive-by malware. Power users are happy, naive users are protected.
If there is a malware that looks like installed by administrator, you have much bigger problems anyway. That malware could patch the firefox binary in the same way as it could deploy the extension, so you gained exactly nothing.
But the current situation just makes power users unhappy. This policy killed some extensions that were shipped by Linux distributions.
I though this change was only about Windows? Chrome on Linux lets me load unsigned extensions just fine.
Apparently the major browser vendors' solution to the problem of things running as users breaking the browser is to remove the ability for users to do things. This is a bogus solution.
See: Firefox's chrome-ification of the plugin system.
The browser vendors then get to take all the "credit" for that. Their decision to remove support for external plugins is absolutely reasonable.
The feature was actively abused my malware so I guess this does makes sense.
That being said, I wish there was a way I could use unsigned plugins easily, without reinstalling firefox.