People complained about people making a full party, and stomping others in 8v8v8, which is why they changed it (whilst also making it that you can only have a party of 4).
It's pretty dumb, those who like playing PvP with friends, and those who play off peak hours are getting hit by the change, whilst premades are just queue-syncing, changing nothing.
I honestly feel like squeenix never knows what to do when it comes to PvP.