Here's what I believe might be an EASY enhancement that would provide a bang-for-buck value by greatly improving ease-of-use and adoption.
In ANY ArcGIS product with a Table of Contents, give users the overwhelmingly popular option to rapidly filter a layer with a simple click of the Layer's symbol classes.
Doing so could apply a standard filter that could be further modified using the current layer filtering functionality. I'm targeting ArcGIS Pro in the title, but this capability should be introduced across all platform variants, IMHO.
This functionality could work on grouped layers in the same way.
The TOC can give a visual indication of the filtered state by graying out (for example) non-visible classes.