I spent nearly two years working on a large codebase with YUI and I agree with everything said here. There are long-standing unfixed bugs, components break on minor version upgrades, there's little transparency into the planning, and there is little incentive to contribute because the contributed fixes never make it into core.
It's still a great library, but it could be so much greater if community was allowed to participate.
It's still a great library, but it could be so much greater if community was allowed to participate.