[seanmcdirmid]

Actually, the graphical aspect of a visual programming language is often an "un-abstraction." Text is pure abstraction with little static context beyond names. VPLs often attempt to provide more context by (a) mixing in execution context (like in Quartz Composer) and (b) through direct mappings to the domain (e.g. a VPL for layout that has you manipulating layouts directly). Much of the usability benefits, as well as scaling problems, that arise in VPLs is due to trying to them trying to be less abstract.