Firefox 44 prevented me from installing completely safe, but unverified extension, until I haven't opened about:config and set xpinstall.signatures.required to false. Question 1: Why Firefox (i.e., its developers) do not give the option to install extension without forcing the above setting? Add whatever amount of warnings if you feel like that. But removing that option is definitely overreaching your (developers') station. Question 2: Will the above config option remain in future versions? I am concerned that developers are trying to remove users from security options choice even in cases when, politely saying, it's none of their business.