Great piece Sarah, the length does the issue justice. The ability to change code easily, using well documented functions has led to WordPress's success - and could just as easily lead to its downfall, as the Plugin repository fills with lots of plugins all doing the same thing, written by people who want to show off how clever their College project is rather than actually wanting to contribute to the wider development on WordPress (or even answer support queries for their own plugin).

That said, any sort of quality control / quality threshold ("what does this plugin do that is *different* to the rest?") would put potentially great authors off - so either way, we're doomed. Dooomed!