Abysea plays it's own part within the community who has in it's own right completed most (if not all) content of FFxi. It's to unwind and do large - small party runs.
They just mention that it *unbalanced the game due to the fact that players only see fit to max out their jobs for that particular content. The problem what (I, in particular)could fix this is relocate the carnivorous maws that transports adventurers to abysea and strategically place them in hard to reach areas (or just area in the past).
Placing them in the present doesn't make areas more usable, it's a distraction to new players whether or not they know the whole roadmap of the MMO (not including rank missions and quest) rather than playing for fun and for the moment (that's how I started).
*Unbalance in a way where most content is being used and others have gone redundant. An example: Hardly nobody does Sea or Sky because everyone find it more fun to be in Abysea and "reck havoc". The only balance (which IMO has worked and should be the only measure to counter-balance the world of Vana diel) that has been implemented were the use of stones and a zone timer. This in turn keeps a balance and control whether or not SE has made adjustments to this and things are easier.