Two critical improvements for plugins:
1) It'll be necessary to grant backward compatibility, otherwise plugins will be lost along the way. Besides, it'll be somehow a mess to align releases as soon as upgrades are released (also because there's no technical documentation).
2) Plugins need far more flexibility and versatility. I agree to the goal of improving platform, but I think it'll be neecssary to open more doors towards plugins' world (i.e. wordpress).
Last point: Andrei, what about a wiki like wp codex? The comunity can work on it, knowledge will increase, and next installations and business.