Well, users need to extend our programs or automate repetitive mechanical tasks, at the end of the day, that's a big part of why computation is so useful. We need to customise how certain actions happen, say how a blur effect is applied to a photo, and presets don't always work. Actually I can't see how tuning some sliders to adjust a certain variable is fundamentally different from setting it via an extension language. This process of adjusting a program or extending it is as natural as cutting a pair of jeans and making it into a pair of shorts.
And this is why I like emacs so much: within it customisability and extendableness is a product of the programming paradigm, and you don't even need to allow the user explicitly. The online docs, the debugger that automatically comes up when needed, the lisp mechanisms like advices and live editing of the running program furnish a great environment where one is not confined to the application designer's decisions, and where making customisations and extensions are really approachable.
And this is why I like emacs so much: within it customisability and extendableness is a product of the programming paradigm, and you don't even need to allow the user explicitly. The online docs, the debugger that automatically comes up when needed, the lisp mechanisms like advices and live editing of the running program furnish a great environment where one is not confined to the application designer's decisions, and where making customisations and extensions are really approachable.