I've found it quite bothersome that instance/dungeon pairing is a cross-world function, yet friend requests and player-to-player communication is not.

Being paired with players on your own server is even less common than being paired with good players. It would be nice to have the ability to communicate with and/or send friend requests to players whom you encounter in instances/dungeons.

Has anyone else thought: "Finally a decent {insert job/class here}!" only to discover that you can't join up with that person again because they're in a different world?

Frustrating huh.