I am on the side of perhaps get better gear but at the same time i have seen tanks undergeared for level 70 Dungeons in SB and they did fine.
At the same token i have come across so many times that tanks have died because healers were too busy doing dps and not healing, so tank dies> agro goes directly to me and i raise the tank (on My Red Mage) and die.
Honestly there is a very good amount of healers that do more dpsing then healing, it seems like the mentality for some.