Really, I think this comes down to the fact that WowAce, not Ace, should be the one being advertised, if anything, to both users and developers. A WowAce mod has easy updating (and uploading), quick bug fixes and translations (thanks to the svn), and a strong, dedicated community.
True; there are several mods around which use the Ace framework but have nothing to do with the Wowace community, and they really have no advantages over any other mod. What makes many Wowace mods worth looking for is the community, forums, SVN, and distribution mechanisms - none of which actually even requires that the Ace framework be used. (In fact, it's not uncommon to see a "Wowace" mod which uses Ace but probably shouldn't...)