"For example, consider a system that is designed completely around events. If one can visualize the inter-connection of components, and one annotates each component with the types of events that it generates (perhaps using expressions), one can easily grasp the overall behavior much more easily than one could if that same design were expressed textually. Thoughts?"
You're making a big assumption that has been contradicted by actual real-world examples. Complexity is hard, and the difficulty has nothing to do with it being in text form. A screen filled with an easy to understand graphical representation is easy to understand because the representation is simple enough to fit on a single screen, not because it's graphical. The systems best able to cope with complexity are textual.
Hardware is also much simpler than software, and it still has bugs. You'll have a hard time finding a complex part that doesn't have an errata sheet. It's also harder and more expensive to debug and test, and typical VHDL makes heavy use of testbenches and simulation to verify individual modules. Conventional software often isn't tested this way. If you want to improve software, encourage adoption of methodologies like unit testing.