I did like it when firefox shrank the space used at the top of the screen. That was my main reason for switching to chrome (I had a netbook and vertical screen

I did like it when firefox shrank the space used at the top of the screen. That was my main reason for switching to chrome (I had a netbook and vertical screen space was valuable), and by the time I became frustrated with chrome and google, Mozilla had improved Firefox in a similar manner and I was able to switch back. I agree with you now though... These UI changes seem like a step back. At best, they are simply arbitrary.