The point of this kind of UI is that they become an extension of yourself. Saying these UI are old and clunky is exactly like saying a keyboard is old and clunky.
Sometimes 2-clicks can be faster than 2x 3-key combo just to make a feature work and also keyboards are old and clunky, ask any k-12 kid today and they will type faster on touch keyboard than a mechanical cherry-mx powered one. People still using text-based only IDEs for productivity are just prolonging the inevitable.
Only when training is lacking. And I don't mean this in a derogatory message, either. People that are trained with a keyboard are pretty much guaranteed to be faster than folks that have only learned to work with a mouse. Discover, though, will be much much faster with an exploratory interface. To that end, the mouse will lead to faster discovery in most cases.