i've also given this alot of thought. rdm is a support class, and there's no room or it in a 4 man dungeon. a pure support job would either be way overpowered in an 8 man or way underpowered in a 4man. i guess they could give it a debuff while supporting like they did to bard but i don't like it.
Since when is Red Mage a pure support job?