Single Sign-on User Profile (Unified Identity Management System)
At its very basic level, there are essentially two key elements which make up a Content Management System: 1) Content and 2) Identity. Currently, Joomla! has NO centralized single-sign-on of its IDENTITY / User Profile, so the users are forced to login more than once, if there is more than ONE key function. For instance, Joomla.org requires the user to register and login to use the Forum, but once logged in, the user can't access OTHER areas, without registering to use that extension as well. With a UNIFIED Profile, all 3rd Party extensions would depend on Joomla's CORE User Profile as the one Identity, to do - anything on the site, once logged in.
John Coonen commented
To clarify, this suggestion for a unified Identity Management System (User Profile) is for Joomla CMS Software itself, not the Joomla Forum.