It's not just about VT100s. It's that text is far and away the go-to format for recording any information that's abstract or has narrative structure. It has been for a very long time.

There are graphical techniques, but they all work in very specific and limited domains. In the wild, even flowcharts that aren't meant to represent a process that has dynamic state are frequently tagged with annotations for explaining important details that are difficult or impossible to convey within the strictures of a flowchart's graphical language.

That's not to say that the idea of a visual programming language is not intriguing, or that it's a waste of time to explore them. But the reasons why it's an uphill battle go far beyond mere inertia.