Visual sound environments are also tools that are taught to music students in conservatories, who don't have any programming ability. These are tools to make sound / art, and people who make sound / art aren't necessarily programmers.
> With text-based code I can read every single character and make sure it's all precisely how I want it.
and when you make art you aren't necessarily looking for the precise. Some people just throw random objects on their patches and wire them almost randomly until it sounds good ; writing the patch is entirely part of the artistic process. That's a completely different mindset that "client wants feature X in Y time, what's the most easy way for me to achieve it".