Hopefully this is just idle state where you obviously wouldn't have combat effects on your screen. But what I notice with the arrow hiding the buffs affecting your character is that it makes it even worse than currently. You don't see what's affecting your character, you don't see stacks, procs and timers on effects that in most cases are essential to not only your optimal performance but the reasonable functioning of your spec. All these things that every player engaging in higher level of difficulty content uses weak auras and add-ons for.
In the current UI all these effects are clumped together to form two or three rolls of icons that you can't rely on to monitor your effects and play accordingly. Just hiding all these icons achievs nothing to improve how the UI informs you of your effects, it just clears the screen. Not that freeing up the room for our add-ons and weak auras is bad, but I'd wish they just weren't needed.