Depends on the problem to solve.
For calculation-heavy tasks i prefer python.
But these days many use R to create shiny-apps which should be done in javascript instead.
Shiny does use javascript; are you against the wrap?
That's one way to look at it.
The other perspective is that with shiny 'many' are able to create interactive apps to display and explore data which would have required 5x as much time to make with js +/- d3