You're looking at this only in short term. Yes right now this is only single, but this is exactly how vagary RoEs were until they later added the weekly RoEs. This is stepwise, this opens the door for the future addition of weekly RoEs, and the possibility of an ambuscade like bonus seal. Though if a seal were to be added and if it only applied to 1 mob players would only likely be using it on aminon for 60k gallamufry.