1. Have it so the group tool gives you a quest (independant of undaunted pledges) which on succesful completion of a dungeon/trial gives you a bronze/silver/gold key once a day.
2. Add individual adventure zone quests and activities (like random delve/anomaly etc) to the queue instead of of just World> Craglorn option and reward a bronze for completion. Maybe even make it like rifts instant adventures where it gives you a list of random objectives to complete though the zone.
But get this...
3. Make bronze keys tradable for silver keys at a 3:1 ratio and silver tradable for gold at a similar ratio via the undaunted quartermaster.
The way I see it that or a similar system would solve the main issues I see with the game, it would give incentives to use the group tool, it would shift peoples focus away from doing just gold key runs and also would give purpose to craglorn and future adventure zones by intertwining them with endgame progression itself.