Because I wanted a strongly typed language that among many good things provides the opportunity for better error messages. Also, the AngelScript compiler is 100% embedded in the application and does not rely on an external environment like Python does. This makes it very easy to install and use AngelCAD.

I know Python is popular, and there is nothing to stop you from developing an alternative front end in Python or any other language of your liking, and still use the AngelCAD boolean engine, just implement the xcsg protocol https://github.com/arnholm/xcsg/wiki