Many of us are very fast with text editors and very expressive with algorithms but struggle with DAW interfaces. Text is just flexible enough to work as a replacement and the already existing tools to manipulate and manage it make it very attractive. Many of the things you pointed out could be handled with various editor macros or possibly even regex. In the case of programming languages, the high level information could be directly encoded by the author of the piece and the low level information could be generated dynamically.

It's a very different perspective on computer UI design and one I personally prefer, although I get why it's not for everyone.