I suggest that the AiN bonus should be per dungeon instead of group of dungeons.

Personally, I do take the bonus as a tank every day I play since is already there for me to take. I would run again but since there is no bonus anymore, I feel lazy to put up with randoms. So unless I know someone who wanna play their DPS class and could use some of shorter queues, I won't tank for randoms unless there is a good reason... like the AiN.