I'm legitimately not sure what use this has, especially with the new system that shows you the units listed sorted by who is most skilled in the relevant labor for the work detail you're looking at.
Dwarf Therapist had this function and it was very useful to get an idea NOW of how many migrants came and what their useful skills were, military talent, etc. DT might be the only way to see it, as it extracts it... somehow from the game data. Or conjectured it. I don't know.
As for my own issue to suggest to the pile... I rather despise the new interface, Steam/classic. The top half of the interface, with the pops/happiness/stocks/date/map, I like. We have had reason to need a quick estimation of those values. But the bottom half...
In particular, I don't see the reason to have the designations exploded out into it's own individual icons to crowd (while little) any part of the screen unless the designation menu was open for whatever you were up to. Even looking at games with a similar elements (rimworld, etc) you don't see this split. It worked for years, I don't see why not it is changing.
Similarly, the map of hotkeys has me annoyed, and the removal of keyboard navigation through all aspects of the interface. It feels extremely slow, and the mouse a hindrance, instead of a help.
I would rather see it returned to a 0.47.x keybindings with the DFHack additions that gave some mouse usability, over the gutted controls we have now. In the long run of a fortress I believe it's easier on the player. Or someway to summon that traditional map of the controls and menus, and and still have the augment of mouse controls as help.