I've seen this question asked at least twice, but so far all of the responses have missed the point of the question.
The Keyboard Configurator generates, on the server side, C source code which it then compiles and provides to the user as a .bin file.
It would be immensely, tremendously, fantastically useful to be given the option of downloading the generated source code instead of/in addition to the compiled binary. This would offer the best of both worlds: the quick creation of an initial configuration via the easy-to-use web-based GUI, followed by iterative tweaking and fine-tuning in a local QMK environment, without having to repeatedly click "compile" on the web UI and then wait for the download.
Is there any reason, technical or legal, why downloading the Configurator-generated source code isn't a possible option?