Canonical has tightened its rules for releasing official editions. Ubuntu, which include Lubuntu, Kubuntu, Ubuntu Budgie, Ubuntu Studio, Xubuntu, Ubuntu Kylin, Ubuntu Mate, Ubuntu Unity, Edubuntu и Ubuntu Cinnamon. These changes were introduced to confirm the readiness of the editions for the final release, which will now only be released if the beta version is successfully completed within the planned timeframe. Changes to packages between the beta and the final release should be minimal and may only include bug fixes.
Source: opennet.ru