Speaking mostly from an Outlaw Rogue perspective here.
The previous personal resource display showed me all the Roll the Bones buffs as well as Blade Flurry and Adrenaline Rush all in one place, non-intrusively, right bellow my character. The new one takes a HUGE space for the same function and shows me stuff I don’t care about (Why is Summarily Dispatched there??). In addition to that it splits Adrenaline Rush and Blade Flurry in an entirely separate bar which makes it take even more space and doesn’t look aesthetic at all, like this is a rough draft you would make in WeakAuras.
“Just don’t use it if you don’t like it” Sure, the only issue is that the previous layout is no longer available. It’s gone. The personal resource display no longer shows you any buff.
Honnestly a buff tracker is an okay feature to implement but instead of creating an entirely new, non-customizable UI, why not just add options to the existing buffs and allow us to pick and choose which ones to display in a separate bar? If you’re going to implement something like this, why not go all the way?