To be honest UI dev tools just plain suck, making everything move more slowly that it needs to. If I'm on the web it's the HTML + CSS clusterfuck, If I'm in C# I'm writing color converters for WPF, if it's Java I have to use the outdated looking Swing, if it's C++ it's QT which I need to doll out cash for. Additionally every smart phone OS has it's own groundbreaking GUI layout concepts and ideas too. Then you get th…
The reality is every platform offers it's own encouraged design patterns and to create the best UX you need to maintain builds for each platform.
In the next 5 years I don't see JS being replaced as that cross-platform runtime, but maybe a transpiled strongly typed language could become defacto.