I'm not sure why you're so adamant that Abyssea should be part of Wings of the Goddess. Sure, Wings of the Goddess hasn't given us any new endgame, but it's given plenty else. Campaign battles. Campaign ops. battlefields. SCNMs. Two new jobs. Some 20-odd new areas (granted, many are reskins) with more to come as we get access to Walk of Echoes...

Abyssea is something else entirely. It's not even all endgame, as evidenced by Abyssea quests being available from level 30 upwards.