Lets review what the article says: addons needed to be signed. The process is automated. It takes only seconds. It prevents some malware from spreading.
You can still host your addon wherever you want. This is just an extra step that can actually improve security. It requires more effort by the part of the developer but it also helps prevent some security issues.
Firefox Dev Edition and Nightly will have switches to turn this off. Firefox stable and Beta will not. Do you want to switch this off? Move to more bleeding edge versions. Or pick the unbranded version.
The unbranded version is available only in English and this is a problem that can be solved with language packs which are available in the hundreds.
Heck, this is an improvement to security. You can opt out by moving to a different Firefox version, there are three versions you can use, DevEdition, Nightly and Unbranded. If you opt-in you have an extra level of confidence in the addon you're installing.
Developers take only couple seconds to submit and retrieve back their addons and the added bonus for security is great. This will prevent those pesky spyware/malware from hijacking your browser which is a problem faced by many users that are not as tech savvy as this crowd here.
And yet people throw a tantrum....