In terms of party composition, this is an issue with the design of PVP, it's free formed and allows the player to change their job before it starts.

If anything what could be done is to create a unique DF experience for PVP solo and 8 player. The solo experience would need 2 DPS, 1 Healer, 1 Tank to form a group and you can't change before it starts. 8 player PVP would need 2 tanks, 2 healers and 4 DPS to engage and you wouldn't be able to change once inside. You change that and then you see how pvp works with the commands since yes, it can be frustrating when it's not a balanced format, since 1 healer makes it harder to keep people alive, 0 healers is pretty much an auto-loss.

They could simply add 2 new DF to the list for both solo queue and the 8v8 queue have them set to a specific party format while keeping the free-form one and then we could see how the concept works when players are always guaranteed a balanced party setup.