First let me say that I am happy with the DC travel system and I am glad it has been added to the game, to remove the barrier of not being able to play with friends who may be on different data centers from your own. It is a great change to eliminate this barrier and it is and was a needed feature.
Also, I obviously don't have any knowledge about the way the backend of this game works, or what technical limitations there might be to a request like this. Regardless of that, I believe this feedback needs to be given because despite the possibility of there being limitations preventing this feedback from being implemented, I think it is an important enough feature that work should be done to work on removing what limitations there might be to prevent it from being added.
Which brings me to the actual feedback/suggestion, as the title implies. With the release of data center travel, on NA specifically (I am not sure about EU/JP/OCE as I do not play in those regions), slowly the raiding scene has transitioned to party finder existing solely on the Aether data center. At the time of writing, on the Primal DC, just after the weekly reset, on Tuesday evening, there are less than 10 parties in the "High-End Duty" category. Even beyond the high-end content, the drought does extend to more "casual" forms of content in the form of groups for older trials/raids, to be done synced or unsynced. Meanwhile on Aether, there are over 100 groups in the high end category and significantly more in the other categories as well.
While it is of course a possible solution for anyone to travel to Aether to join these parties, I believe it's impractical/unsustainable for PF to keep working in this way. Particularly when new content is released next year going into Dawntrail, the influx of people going to Aether to join PFs is going to make it a worse experience for everyone; people who call the Aether worlds their home, which will now be more congested as a result of the travelling, and for the travelers themselves, who may find themselves unable to raid/long queue times to get in as well.
I believe that the best solution to this problem is to make the party finder work cross-DC, similar to how it currently works across worlds within a DC. This would allow players to sit in their house, island sanctuary, use retainers, etc. And it would keep the populations across the Data Centers more balanced. Lastly it would make it easier to find groups for "niche" content, like older raids/trials, BLU, min ilevel/no echo groups, etc., because all listings would be viewable no matter what DC you are on.
Again, I am assuming there is some technical limitations to this given the way that data center travel currently requires one to log out of the game and log back in just to travel to another DC. However, I believe it is an important problem to solve and I hope that Square Enix can consider the benefits of changing the back end to allow this feature to exist.