I was going trough wikipedia after your comment, browsing different visual programming languages and paradigms. I suppose you're right that they don't scale in the same way as textual languages. Maybe someone finds a good set of constraints to make them scaleable and the elements abstractable.

Anyway, they do have niche success (if not in general programming); and some of Bret's explorable explanations ideas [1,2,3] seem to point away from textual programming.

[1] http://worrydream.com/#!/ExplorableExplanations [2] http://worrydream.com/#!/InteractiveExplorationOfADynamicalS... [3] http://worrydream.com/#!/LadderOfAbstraction