> Maybe because I try to keep my code composable I don't have to change it in many places? But this isn't limited to Common Lisp for personal projects: also bigger projects with multiple persons at work in C++, Python, etc. refactoring isn't such a big thing that I'd use it as an argument when chosing programming languages.

I find refactoring is the most important part of programming; as the problem (or one's understanding of it) evolves, the code that describes it needs to evolve to match. When I worked in Python I found that I hit a wall where as my codebase got bigger, changes to my model took longer and longer to apply, because I had no way of reliably knowing what was coupled to what else; types solved that.

(I like lightweight syntax but not to the extent of giving up infix operators/methods)