It took me renewing my sub in Shadowbringers to start slinging AoE spells on groups as SMN. I always always always used single-target until someone in an FC I was in mentioned using AoE spells (that by virtue of the dungeon we were in I didn't have access to at the time). As soon as I was able to, I started slinging AoEs anytime there was more than two enemies.

Also, I'm afraid to do Expert as anything other than DPS.