Graphical programming also walks away from a huge body of work dedicated to managing, searching, and manipulating text. As good as the graphical tools can be, there's nothing like all the work that's gone into text editors, diff tools, query languages, etc. These are all things that are central parts of my programming workflow, and they are all missing or considerably weaker in a graphical language. (This is not to mention the fact that graphical programming gives up two hands and ten fingers as input devices in favor of one hand pointing and clicking with a mouse.)
I think as appealing as the idea is, whatever benefits there are don't outweigh the considerable costs.