To give a bit of context, the idea behind this design is that those scripts should ultimately only be glue scripts that convert from some editor agnostic tools

To give a bit of context, the idea behind this design is that those scripts should ultimately only be glue scripts that convert from some editor agnostic tools into Kakoune commands. I do agree that sh is not a nice programing language, and forking programs all the time is not very efficient. I think that there is a tradeoff between the different approaches, and Kakoune's has proven to make quick'n'dirty very easy while being suboptimal for complex tasks. I am okay with that tradeoff because I still believe most complex tasks do not need to be editor specific, and should be provided by separate tools written in a more maintainable language. Another reason is that I've been trying to design Kakoune in a minimalistic way, and one thing I tried to unify was the user and scripting interface, which means I needed a command language that was easy to write interactively (`edit filename` vs `edit("filename")`). This is again a tradeoff that helps with simple things (as users already know the scripting language if they know how to use the editor), while making complex things harder.