Earlier quoted context omitted.
Australis wasn't necessary at all, though. It broke my ability to keep tabs on the bottom, it forced the refresh button into my URL bar (the opposite end of my other navigation buttons ... making it much more annoying to use), it killed my stop button, it took the bookmark icon out of my URL bar, and it broke my ability to see full page titles. None of this enhanced anyone's productivity: it was change for the sake o…
It's really a matter of taste. I understand that you feel it wasn't necessary, and so the change was annoying. But other people felt the look was dated, and well over-due for a refresh. I guess the Firefox developers were in that group.
Is the UI of a piece of software actually a fashion statement?
Should these decisions not be evidence based in some way?
(I use Firefox 39 on Linux and have no strong opinions either way - just interested in the process)