If a rating and works/doesn't-work system was built into the WordPress plugin list / framework, then wordpress.org could pull a plugin if it hasn't been updated in X days/months/years *and* it gets too many "doesn't work" reports. If it's old, but it works fine, then no need to pull it. The current rating and works/doesn't-work system on wordpress.org isn't used by the majority of users, and so cannot be counted on for accurate metrics. A built-in system of reporting would be the way to go, IMHO. ;-)