If you have a toon that is only good for buffing, you end up like the Pallies in WoW before they were actually made useful for raids. They all had to hangout outside of the instance and buff everyone after wipes. Unless the buffs are absolutely indispensable and have a duration that's shorter than a boss fight, buff bots are not going to be in group in a min/max situation.
GW2 had combos like you described where shooting through a fire aoe added fire to the attack, or melee could charge through it and maybe get a fire shield. I thought that was one of the more clever things GW2 did well, and I would love to see that kind of synergy with Wildstar's attacks. It seems that the combat system would be ideally suited for it.
Check out this old school bad ass synergy:
GW2 had combos like you described where shooting through a fire aoe added fire to the attack, or melee could charge through it and maybe get a fire shield. I thought that was one of the more clever things GW2 did well, and I would love to see that kind of synergy with Wildstar's attacks. It seems that the combat system would be ideally suited for it.
Check out this old school bad ass synergy: