com_plugins can't load a config.xml file

This is the tracker link: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32929&start=0

The com_plugins component, doesn't  recognise params form from a config.xml file, only if the config tag is inside the manifest file.
 
This is inconsistent since we can use a config.xml file in components and modules, why not in plugins?