Maybe healers should be given access to Hallowed Ground, Sentinel and Rampart. What if the tank disconnects? The party still needs to complete the dungeon or even Ultimate raid.

However, giving defensive cooldowns to only healers may be too selfish. Perhaps give Hallowed Ground and other defensive cooldowns to DPS job like Black Mage and Ninja. Black Mage and Ninja used to have access to Hallowed Ground for one to two attacks with Manawall and Perfect Dodge.

The party can share the load and everyone can tank too. No more tank anxiety.