Overhaul of the Layer Style panel UI
The controls to define the in/out points are not intuitive: pressing alt+click-drag isn't discovered easily.
Doing them "à la Lightroom" white/highlight/shadow/black would be a lot more intuitive.
I think that by doing an UXP styled redesign the Blend-If section of the Layer Style panel would get noticed more often/earlier.
A long, long, long long long time ago I figured out for myself how the Blend-If controls work (this was pre facebook kids)
Now, 15 years of professional photoshopping later (in fast evolving teams) I still notice how little this feature is known/used.
Hope it helps. :-)