[tbabb]

I think one reason is self-selection bias: Because all programming languages are text, everyone who is a programmer is necessarily adept, comfortable, and intimately familiar with representing programs as text.

There is a whole other kind of programmer which doesn't exist yet— a visual coder— all of whom are doing something else right now, because there are no tools for them. It takes a large leap of imagination for a text-coder to empathize with these still non-existent visual-coders and make the tool that they need, and a large leap of imagination to envision a complete visual coding system from the ground up which can be used to solve actual problems and compete with the very mature text code tools that are already out there.

In short, "massive amounts of cultural inertia".