Generally these 'archaic' desktop apps have much better UIs than all the flat mobile-focused UIs that are popular these days with their oodles of wasted screen space, messy menus and unnecessary extra clicks needed for basic operations.
Why do you think that is? What makes them popular?
Figma, canva etc are all really popular. Google docs is popular. They are all easy to use. For basic tasks we really dont need a huge expanse of menus and options all laid out like an aircraft cockpit. I would argue for a normal person that is far worse than some empty screen, which maybe hides a bit, but puts the more common or important tools visually first.
Maybe it could just be a toggle in a menu somewhere, "pro mode". These FOSS tools could learn what was good about modern design and try to iterate on the good take aways.
