It will not fix the many UX issues that exist, but it could at least guide the new users through the first two or three steps in getting started. What i would propose as at least a start, is a "Getting started wizard" that customizes the UI and settings to suit the new users needs. This is exactly what my colleagues did, and probably what many other engineering forums users also have done. You click all sort of different buttons, watch some "Part Tutorials" on youtube, get scared of booleans and an unusual looking model tree, and uninstalls FreeCAD. However, you have never learned CSG, and want to design the modern way with sketches and features. You see a workbench selector, and navigate to "Part", because that's what you want to make. You open FreeCAD, and have no clue where to start. I would guess, without any data, that this is a moderate amount of the userbase. Say you are a mechanical engineer, MCAD hobbyist or a student, coming from another paid software you use at work or learned at uni, and want a free CAD for home use. Yes of course there is always a few savants that are able to pick up FreeCAD in a matter of hours and be productive in days, but that is most definately the minority, not the rule.
I think the lack of guiding or hand-holding that other software provides is the main issue. In my opinion the "FreeCAD learing curve issue" is not caused by 3D modelling being inherently difficult or by an old looking UI. Watch the first five minutes of this video, please.Rationale: not really needed, but if you need a reason for such a wizard to exist, here is a small list:
FREECAD GETTING STARTED INSTALL
Multiple forum threads in the last months/years has mentioned that a Welcome Wizard that shows up on a new install would be a great tool to guide new users to a better default FreeCAD experience.