There is a lot of unnecessary back-and-forth on the symbology tab when putting together a composite symbol. It's one tab to add, delete, reorder, and add effects; another to modify the classes or said effects. I often find myself dragging the classes on the layers tab in an attempt to reorder them, forgetting that I have to click onto the wrench tab, drag it there (or make whatever modification I'm needing), and click back. There's not enough on that wrench tab to justify the extra clicking.
I picture something like this.

Heck, you could probably take it a step further and just put everything global at the top and the sub-layer controls at the bottom, eliminating the paintbrush tab too?

Just some thoughts. Anything to reduce the amount of back-and-forth in Pro I'm all for.