At this point adding a 4th role is likely not going to work.

FFXI essentially had 4 roles (5 if you were one of the people calling "puller" a role), however basic party composition had 6 member slots. Thus it could fit Tank, Healer, Support, DPS.

A majority of party content in this game has 4 man groups. So either we split the comp to 1 each of tank, healer, dps, support or we just make the support queue as DPS and run the risk of having tank healer support support and having a very long duty run. Instead I think SE has tried to break down the support role into support skills scattered across all jobs however it feels like certain support aspects lacking outside of possibly ranged physical DPS.