I moved from Visual Basic (3 no less!) to C because I needed to optimize the performance of a software synthesis (like, sound synthesis) application I was developing at the time (mid-1990s). It boggles my mind to this day how much fucking work you had to do just to create a simple window in C. It instantly made clear why UIs at the time were so bad and I went back to Visual Basic for the UI with a compiled C DLL to do the heavy lifting.
There's no excuse for why UIs are still so bad today.