If it hasn't been mentioned before, AutoHotKey is an alternative to waiting years for the devs to get around to planning to plan to put in it in the planning stage for future talks about the next stage of potentially planning.I also use X-Mouse Butto...
It's hard to imagine any good reason why this change was made other than maybe as some sort of convenience for the Mozilla development team.
At least that's all I can imagine anyway because I've seen precisely zero users wishing for a separate privat...