As the curse of Australis on Firefox approaches, I think this commenter at Ars Technica said it best.
That so called "unnecessary clutter" consists of all the features that made Firefox so popular in the first place. The Firefox developers are insane and have spent the past 2 years hard at work destroying everything that made Firefox the best browser available.
I’ve mentioned it before, but I used to advise companies and users I assisted to use Firefox and no other browser. Since the Firefox developers have determined they need to destroy it, I no longer advise anyone to switch to Firefox as you never know what they will take away next.
I personally will keep using Firefox for as long as I can modify it enough to be functional, which takes longer and longer these days (about six hours of work now). But regular users won’t and generally cannot do this.
Unless you’ve ever done something like compiled your own program, just use whatever the default browser on your OS is, which is probably IE. Firefox is no longer worth switching to and is likely to continue getting worse.