The clear advantage of text-based programming languages for complex programs is that all the wires and arrows are represented by symbolic names. Instead of drawing a wire, you simply use an entity with the same name (be it a variable, a function, or a data type). This is much closer to natural languages than a tangled mess of wires which becomes unmanageable after a certain level of complexity.
Having recently finished playing MHRD I think there are contexts where the graphical representation is a lot more clear. Granted, that game's language is at a very low level where you write your wires kinda DOT-esque, but I basically had to draw everything from the ALU onwards on paper first.
