Pushing back on this point because the way I'm reading this it seems to say that by giving the user the option to choose a beginner UI that they won't venture beyond the tools displayed because we've placed a limitation on them. To me it seems that as a user naturally starts to get better at a program they start exploring other parts of it. It's not like we're hiding the rest of FreeCAD functionalities without their consent. The wizard gives them this option and informs them that FreeCAD is very wide in scope.
80/20 Rule: 80% of time spent using 20% of the application.
Edit: as for radical change of the UI... I think realthunder has shown great promise in this area. We don't need to make enormous changes at once. This wizard proposal is another step toward change. Small steps at a time.