I think a really simple thing they could add to help build community is make it easy to see if players you team up with in Duty Finder are on the same server as you. Maybe make their name a different color or have an icon next to their name.

My reasoning is that we do most of our interaction with each other through Duty Finder with people from random servers. I don't bother to remember the names of random people I play with because I figure 'what are the odds I'll see them again? not likely'. But if I could identify who in my Duty Finder party is on my same server, I'd be more likely to remember them and maybe even seek them out after the Dungeon is over to be friends.

I know I could just ask "hey what server are you all from?" every Duty Finder run I do... But it would be really convenient if you could just see who's on the same server (especially for new players trying to make friends)