Please read the whole proposal before commenting.
With the prospect of achievements (and possibly titles) being made account-wide, and in conjunction with the gear sticker-book, there will be less replayability in dungeons.
To add a new layer of replayability, I propose that all DLC dungeons have leaderboard mechanics/scores added to them.
This will give the endgame community a whole new experience and will be even more benefitial for those who either can't find a whole raid group to play at the same time, or can't/don't want to commit to a full raid team.
To prevent the 'toxicity' (that many players complain about in endgame players) spreading into your average player's daily pledge, this added feature should NOT apply to groups formed in the group finder tool. Groups wishing to push for a scored run will need to travel directly into the dungeon, like we already see with trials and arenas.
The leaderboards would be active for all DLC dungeons, with a 'weekly' leaderboard rotating, giving gold jewelry to those who make it on there. This may slightly reduce the number of players in PvP due to a slightly reduced reason to farm AP, however with each character only getting 1 or 2 pieces of jewelry from one of 3 sets from one the ever growing list of DLC dungeons it will still be a significant grind and therefore the golden vendor will still have it's place.
In summary, apart from the daily DLC pledge, there isn't many completing these dungeons, which is sad because in my opinion it's some of the best designed content in the game. Once players have collected all the gear in their sticjer books and have the title given across all characters, this will only get worse. This is quite a simple feature to add to the game with lot's of benefits to many players and very few (if any) drawbacks.