You are right, building a good UI for the desktop has become exceedingly difficult. In my experience new UI toolkits try to mimic the web experience (kivy, QML, Slint, Flutter, etc.) and end up being threadbare with the simplest widgets available. In my opinion, every new UI toolkit since QtWidgets/WinForms/Delphi/WPF/Win32/Gtkmm era has missed the point. The desktop is a power tool and requires powerful widgets. Virtualized lists, data grid with complex interactions, drag and drop, OS integration, modals, background tasks, docking windows, etc. A toolkit that puts a slider, some text and buttons on the screen doesn’t solve the harder problems and the web browser will run circles around that workflow. Easier UX can be built in anything really. Until there’s a desktop app framework that solves the hard problems in desktop UI dev then desktop will languish and hard stuff will continue to be hard.