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.
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.