It is entirely because new content/gear (Su5/REMA augments) that is intended to be a selling point from the devs' POV was effectively requiring group-play oriented BST to intentionally make it harder to play in a group. Changing the Job Point category removes that roadblock for BST to do the new stuff without worries. If the Pet:Enmity+ category did not interact with the newest grind, the change would most likely not have happened.
It probably helped that the player who brought up the issue made a convincing and logical argument w/o whining about it, (and did so in the devs' native language.)